Looking in the activity stream, a few others seem to apparently be able to access blogs and member profiles. I logged out and blogs reappeared. Logged back in and got the error again. Several users on an IRC channel that is unofficially part of the site said they had no problems, but one other user is affected just as I am.
So strangely, it seems to be limited to only certain users. Bizarre. It's not userclass-based, either, as that user having problems is just a regular user, and I'm administrator.
I tried running vB's tools to rebuild stuff but it seems to have no effect.