Thailand Blogs is a collective of blogs by people in Thailand and Thai expats. (Fantastic round-up of the various blogs, detailed background.)
Jot Man, which is an actual blog. (English is not the writer's first language, but awesome pics and detailed descriptions of what's going on in them.)
2Bangkok, which looks like like a blog coupled with a few newsy touches. (Confusingly organized.)
thailand is discussing it in this post.
Other LJ users blogging the coup: badsmurf, jethaina (scroll down beyond the top sticky post), erussell, and shivwuffy