The TechEd slides and video are now up!! There are literally hundreds of sessions you can watch (the exact same ones that you would have been sitting through if you'd been there), and the powerpoint slides are available to download. The slides look great in Keynote, although the site seems to have some issues with Safari.
I watched tons of the slides up after the PDC which had some amazing info about all the stuff that they were working on for Longhorn. I would work on two monitors and would put the video feed up on the third. I watched the overviews of all the new technologies (Avalon, Indigo and WinFS) and then watched in depth reviews of all the stuff that I was interested in.
This time I'm going to watch a lot of the Security , Developer Tools and Technologies and the Architecture talks since they interest me the most. Then I'll probably watch the high level talks for the other sections and see if there's anything cool going on in those other areas.