Posting from Las Vegas ... Internet Explorer 8, the next version of Microsoft's Web browser, was demonstrated publicly for the first time just now at the company's Mix08 conference here. IE GM Dean Hachamovitch showed two new features for end users, which the company is calling "Activities" and "WebSlices."

The Activities feature lets users highlight text on a Web page and click a button to use the highlighted words in various online services, such as an eBay product search. WebSlices will let users subscribe to specific content within a Web site. On stage, Hachamovitch showed the ability to hover over a feed on his Facebook page to make a small WebSlices icon appear. He was then able to click on the icon to subscribe to the feed in his IE8 favorites bar.

Microsoft's Channel 10 site has video of the features.

The idea of tracking specific elements of Web pages isn't new. Apple takes a different approach with its Web Clip feature in Mac OS X, essentially letting users capture any portion of a Web site and move that image into a Dashboard widget that changes as the site is updated. As demonstrated by Microsoft, the content available for subscription through WebSlices looks like it will be determined by the site's developer.

Hachamovitch didn't talk about a time frame for general availability of IE8, but he said the company is making a beta version available to Web developers starting today. The WebSlices and Activities features will depend in part on Web developers offering the technologies through their sites. Hachamovitch noted that there will be other new features in the final version of IE8 that he didn't show today.

Update, 11:50 a.m. Via Microsoft, images of WebSlices (top) and Activities: