From Scoble comes screenshots from Longhorn showing some cool features, including integration with hardware-based auxillary displays, similar to those that have appeared on cell phones in recent years, and improved support for contacts, including the potential to have a "communications history."
Windows has included an integrated contact management application, dubbed Windows Address Book, for several years, but in Longhorn, the Contacts library will gain new precedence and will likely be adopted by the Office team for Outlook, and by numerous third parties. Microsoft has big plans for the Contacts library in Longhorn, though those dreams are only partially realized in build 4074. Eventually, you will be able to connect Contacts to numerous portable devices (like cell phones) through the Longhorn SyncManager infrastructure, connect electronically with nearby contacts for peer-to-peer collaboration and file sharing, and perform other duties which are either impossible today or require an extensive collection of third party software, much of which doesn't currently work together. One of the more intriguing parts of this work is the Communications History view, which will chronologically detail all of the phone, email, instant messaging (IM), peer-to-peer, or other conversations you've had with contacts. The Communications History view can be sorted by date, rating, message type, and other criteria.
For someone like me, who eschews the Welcome Screen (and with it, Fast User Switching) for the more secure Windows 2000-style login screen, this feature might have gone to waste. However, someone at Microsoft thought that it was a good idea to document how mail programs could modify this feature. Despite the article's outdated claim that, "there are only two programs that support this feature: Microsoft Outlook Express and Microsoft Windows Messenger" (which does not even seem to include Microsoft Outlook), the good people at Mozilla added this as a feature to Firefox (I could not find the bugzilla reference to the actual registry-manipulating feature in Thunderbird/Mozilla Mail).