The two new headline capabilities in IE8 are Activities and WebSlices. Both are designed to add functionality from third-party services without requiring you to leave the page you're viewing.
The Activities feature reminds me a bit of Yahoo! Shortcuts which, when you hover the cursor over dot-underlined text, pops up options that let you, for example, map a place name or add an e-mail address contact list. Activity options in IE8 include Translate, Send, Map, Find, Define, and Blog. Just by highlighting a paragraph, I got a northeast-pointing green arrow that dropped down choices for Activities I'd installed. I was thinking my "Find product with eBay" action would display in the first list, but it was available only from "More activities." The feature is as a bit flaky at this point: It would work the first time I used it in a page, and then I'd have to reload the page to see it again.
When I highlighted the text "MacBook Air" on the PCMag.com site, I was rewarded with the Activity arrow/drop-down and was able to map the nearest location—Muskoka Airport—in a small window over the page. Hmm. Clearly there's some work to be done here, since and airport doesn't really have a lot to do with a laptop that happens to have "air" in its name, but it shows the technology's potential. I was unable to find any results in the eBay Activity, but its small window is brimming with potential. You don't even have to click on the activity you want in the arrow drop-down; just hover the mouse over it, and, in this case, for example, a map displays.
Activities worked with some sites and not others, seemingly at random: They worked on PCMag.com but not on Yahoo! or The New York Times site. Microsoft has provided developers with documentation for building their own Activities. With its new push towards openness, the company is making the technology behind both Activities and WebSlices available under a wide mix of licenses, including Public Domain, Creative Commons, free BSD (for copyrights), and the Microsoft Open Specification Promise (for patents). This should increase the appeal of the new features to independent developers.
While we're on the topic of developer help, I should mention Integrated developer tools, accessible from that small arrow icon up on the right side of the toolbar. This brings up a window showing the site's HTML, CSS, and JavaScript in a visual debugging environment. The tool give developers more than the typical browser's "View Source Code" choice, showing IE's internal representation of the site.
The second major new feature, WebSlices, lets you subscribe to content within a page, provided the site's developers have enabled the feature. So far, sample WebSlice-capable sites include StumbleUpon and eBay which let you quickly display an updated window of hot sites or auction items, respectively. Setting up a WebSlice from such a site is simple. When your mouse is over the sliceable area, you'll see that part of a page is boxed with a thin line, and a purple icon with circles will appear at the upper-left-hand corner of the box. Clicking on the purple button brings up a small confirmation dialog stating the name and source of the WebSlice.
When you've added a WebSlice, a link for it appears on your toolbar, just as with any other Favorite. But this toolbar button drops down a partial page window, rather than navigating you to a full Web page. An "Open" choice at the bottom of the mini window navigates you to the full site. Also, when you're on a site that supports WebSlices, your RSS toolbar button changes to the same purple circle icon, and clicking it drops down all the slice choices on the page, for instant subscription and adding to your Favorites toolbar.
When one of your WebSlices has new or changed content, its toolbar entry will have bold text to notify you. The feature seems like it could be useful for those who want to keep track of a single eBay item or news topic, but it also seems to put too much onus on site developers; it would be nice if the feature also worked with standard RSS or Atom feeds. The RSS reader in IE8, incidentally, remains similar to IE7's, displaying in the sidebar, though now WebSlices appear along with regular feeds
