Rivera's WithinWindows site, which hosted shots of the new tablet user interface, has already buckled under the massive amounts of traffic. Thurrot has the shots as well, and they show a tablet variant of Internet Explorer 9, which looks a lot like the Windows Phone 7 IE, except with the IE9 rendering engine, of course. Browser history is implemented as WP7-stile tiles (like 'tabs' in Windows Phone 7 IE).
The PDF reader, dubbed Modern Reader, also takes a lot of cues from the Metro design language. The back button, the page scrubber - it's instantly recognisable for a Windows Phone 7 user such as myself. This is a major step for Microsoft, and one that many of us have been longing for for a while now: a native, pre-installed PDF reader for Windows. It will be interesting to see if any anti-trust concerns pop up from Adobe, which gets the bulk of its traffic from PDF Reader downloads for Windows.
What is more interesting, perhaps, about Modern Reader than its Metro user interface is the fact that the application is built for the new AppX package format, which will allow developers to package applications for deployment among all form factors - tablets, phones, and regular computers. Microsoft intends to allow developers to easily scale their existing Windows Phone 7 applications to use AppX.
Thurrot and Rivera claim that Windows 8 and Windows Phone 8 (codenamed 'Apollo') will both standardise on the AppX application format. That's one fine incentive for developers - write your application, and have it scale from phones to tablets to desktops. Apple already offers something similar, of course, so Microsoft is a tad bit late to the game.