It acts as a (fairly) fully featured local journal, with obvious similarities to an LJ, but also sends all items to a 'real' LJ when they're posted (and resyncs any updates made through a cron job) through the 'FLAT' interface. 'Friends' and 'Private' privs are mapped to permission groups in the remote journal, allowing people with an account on your site, but not LJ, to see your friends posts if you want them to.
It's written in PHP - it doesn't do multiple journals yet though, so I'm posting this through the web interface.
Anyway - that's what I'm doing, but the point of this post is as follows: *how* do I know when a post has been deleted at LJ? Syncitems returns no mention of the removed post - is that my only clue!??! The docs are blank on this one...