You run it from your shell, then it launches your $EDITOR.
It can post to multiple accounts on multiple servers / services.
So it could post to 2 LJ accounts, 1 DeadJournal account, and your Slashdot journal, all at once.
The Slash support is coming, but not from me. I just stubbed it for now.
Oh, if you want current mood/music/security, just add below the Subject: line: (case doesn't matter)
Security: friends or private