About a week back Microsoft announced Internet Explorer 8 at the MIX08 conference and most interesting part is that a developer beta is now available for download.
You can go ahead and download the beta here
What's New in IE8?
Firstly, IE8 comes with lot of changes in it's internal architecture that improves readability, performance, and scalability of the browser.
Now, How it works, Andy Zeigler, Program Manager on IE Foundation Team at Microsoft explains some of the details.
Andy Zeigler Said:
You may have noticed that computers come pre-loaded with all sorts of software. While a lot of this software is useful and works well, some of it, including IE add-ons, can crash and interfere with your browsing experience. Internet Explorer 3rd-party add-ons are COM-based, which enables developers to write high-performance add-ons with powerful features. This also means that IE and running add-ons share the same process and memory address space, so when an add-on crashes, it causes the whole browser to crash. According to an analysis we did of our Windows Error Reporting data, over 70% of all IE hangs and crashes are caused by 3rd-party add-ons. We work closely with software vendors of the most frequently installed IE add-ons to help improve the quality of their add-ons. However, due to the large number available add-ons, it is difficult to provide outreach to every developer.
The IE Process Model
Part of what we’ve done with LCIE is to split the frame from the tabs, and allow them to function more autonomously. As a refresher, here’s a somewhat simplified view of the IE7 process model
In the IE7 model, each browser window (UI Frame) usually has its own process. There are a couple of exceptions. For example, if you press ctrl-n to open a new window, IE creates a new UI frame in the same process. The tabs, toolbar extensions, browser helper objects, and ActiveX controls all reside in the same process as the browser window. The problem with this model is that a single access violation, stack overflow, or any other type of failure will cause your entire browser, and all its tabs, to crash.
Below is a diagram of how we’ve changed the process model in IE8.
There are a number of notable changes here:
- Tabs are isolated from the frame, and are located in separate processes
This gives IE the opportunity to isolate many failures to the tab process, thereby reducing the amount of damage done to the rest of your browsing session. - The frame and the broker object are located in the same process
This is a win for startup performance. The broker object is responsible for examining a URL, and determining if it should be loaded under Protected Mode or not, and launching IE at the appropriate integrity level. We no longer have to wait for the protected mode broker object’s process to startup before loading the rest of the browser.
- Low and Medium integrity tabs can reside in the same UI frame
The Windows Integrity Mechanism operates on a per-process basis. Now that we can place tabs into their own processes, we can turn Protected Mode on or off on a per-tab basis. This is a big usability improvement. You no longer need separate browser windows to view sites in and out of protected mode.
Now, that's one major change that truly addresses IE's past issues.
What's next!, Yes, Now come the interesting part, something for developers, so let me proceed with what's in the box for my dev mates. 
IE8 Developer Tools
All this time there were tools which offered help to web developers to developer and debug apps for IE, but mostly came as third party tools. One of the most popular tools that came as a toolbar from IE Team was the IE Developer Toolbar, which offered huge time saving and productive tools to help web developers to debug their apps.
IE8 Developer Tools provides huge improvements and productive tools to help developers build better and stable apps in no time.
What kind of tools and improvements does IE8 Developer Tools offer?
- Internet Explorer 8 simplifies the process of debugging by including developer tools out of the box and making those tools easy to use. Instead of having to find, download, and install a separate debugging application, just press SHIFT+F12, or click the developer tools icon in the command bar.
- In addition to simplifying the debugging process, IE8 Developer Tools offer a new perspective on your site. Instead of just a source view, the tool provides visibility into Internet Explorer’s internal representation of the site. For example, the DOM tree in the tool is built from the tree IE builds internally to display the page, not from your source. So if script changes the tree, IE8 shows you the updated tree.
- The Internet Explorer 8 Developer Tools also provide the ability to experiment and iterate rapidly by letting you edit a site within IE. For example, once you’ve found a style rule or property you’re interested in, click a checkbox to enable or disable it, or click an attributes in the DOM tree to edit it in-place
- The tools also provide easy access to all available rendering modes so you can test different modes quickly.
IE8 Improvements And New Features
Domain Highlighting
At a glance, the most visible change with IE8 is Domain Highlighting. Internet Explorer 8 will automatically highlight what it considers to be the owning domain of whatever site you’re currently viewing. This helps users identify the real site they’re on when a website attempts to deceive them. The screen shot below shows how IE8’s Domain Highlighting can help users spot these attacks
Support For Pasting Multi-Line URLs
IE8 will automatically strip out excess carriage returns and line feeds within a URL when pasted into the Address Bar. Many web e-mail applications automatically split long lines into multiple lines, which meant you couldn’t easily copy and paste them into the browser. Users can now highlight an entire URL, no matter how many lines it spans, and paste it directly into the Address Bar.
Example: if you copy and paste the next 3 lines into the Address Bar of IE7, only the first line (an incomplete fragment of the entire URL) will appear. In IE8, the entire URL will appear:
http:/
/www.chiragbatra.com/
blog/default.aspx
New Functionality on the Favorites bar:
The Favorites bar, previously known as the Links toolbar, has been updated with great new functionality that helps you get information from your favorite websites quickly and easily. The new IE8 Favorites bar still has your favorite links just one click away, but also allows you to add WebSlices (new feature debuting in IE8) and feeds to the Favorites bar, facilitating your navigation experience. The WebSlices and feeds on the Favorites bar will check for updates to content on your favorite websites without requiring navigation to those websites.
WebSlice
WebSlices bring your favorite pieces of the web with you. WebSlices are portions of a webpage that you can subscribe to and view updates directly from the Favorites bar.
WebSlices let you subscribe to a portion of webpage to get updates and view these changes without having to go back to the site. Let’s say that you’re an eBay, and you’ve got your heart set on a 80’s Swatch watch. With WebSlices, I can subscribe to the auction item and know when there is a price change directly on the browser chrome.
try out WebSlices on these sites
Activities
This is another great feature that comes with IE8, with Activities, you can access your services from any webpage. Activities simplify the common task of copying, navigating, and pasting into a single action. Just make a selection and click on the Activity button or context menu to view your services.
Here are some other Activities that you may find helpful:
Cheers!