Here at Mix08 in Las Vegas, IE head honcho Dean Hachamovitch has introduced Internet Explorer 8, which he told us will be available for beta download later today.

The big features are CSS 2.1 standards compliance (now the default), and two new things called Activities and Web Slices.

Activities are a way of installing browser add-ons that enables new instant links. You can select text in a web page, right-click, and get links for things like “buy on eBay” or “see user reviews”. This is enabled by an XML specification called the OpenService Architecture, which is being released under the Microsoft Open Specification Promise.

Web Slices are a way of subscribing to page fragments, or perhaps pagelets (my term). This then appear as links in the IE8 toolbar. Examples we were shown were an eBay auction, and Facebook feeds. Like Activities, this is enabled by an XML specification, this one called the Web Slices Specification. The page author determines what content ends up in the pagelet.

If the specifications catch on, I imagine other browsers could easily implement them.

Activities remind me of the almost-dead Smart Tags, in the way that they enable a new in-page menu of options related to a keyword or phrase. The difference is that there is no auto-recognition; the user has to select some text and right-click.

Finally, we saw some great developer tools for debugging JavaScript and CSS. In particular, I liked the feature which lets you select an element and discover which CSS rule is winning in the rendered page.

Note: Post edited to clarify how Activities work. I misunderstood these at first, thinking they were extra links authored into a page. Apparently they are not: you have to select some text and then use a pop-up menu. The advantage is that we will not get pages festooned with extra links. The disadvantage is that you can easily select text that returns no meaningful result.

I rather liked the idea of multiple destinations for a single link, but it seems this isn’t it.