I'm planning to add to this list. I know, the best laid plans...
Here's my first pick for best blog of the O'Reilly Emerging Technology conference: Ross Mayfield's blog. He magnificently propounds the social software perspective, so if you like that stuff, this is treasure to those of us who couldn't be there. He does a post for each session he attended. Hard worker, that Ross. And insightful, pithy reporting and commentary!
Here's a snippet from his Transcendental Social Networking post that really piqued my curiosity:
Motto: Don't build application, build contexts for interaction... Instant chat. Groups are objects. Using the social network as a whitelist.
OK, you should go to the O'Reilly Network ETcon page too. They have tons of links to coverage of the conference.