Edit: Well, that's certainly bizarre. LiveJournal implements the Blogger API (at http://www.livejournal.com/interface/blogger, if you've got a Blogger client handy), and I found a GAIM plugin for Blogger. I sort of expected a "blog this" context menu, but no, it implements Blogger as an IM protocol. Your friends list appears in your buddy list in GAIM, and if you "send an IM" to your own blogger-user, it shows up as a post. The analogy is a bit strained to say the least.
What I want is a way to highlight a URL or a bunch of text and go 'post this!' and have it show up in Logjam or Drivel. I guess I'll settle with cut and paste, because this Blogger plugin is bizarre.