if you use jabber you might be interested to know that jabber watcher went live today. it’s an information service that provides instant notifications on topics of interest from venues such as slashdot, freshmeat and moreover.
before it went live there was an interesting discussion on the scalability of “agent”-like services that live on your roster [ analogous to active buddy ] and subscription-like information services such as jabber watcher. i think the general consensus was that the jabber server wouldn’t scale so well with “agent”-like services that live in your roster because of the way that presence is determined:
“I talked about this with a few Jabber.com
developers this morning and we all agree
that the best approach is probably for bots
to be services rather than clients. The
downside is that they have to deal with
their own rosters and presence, but the
upside is that they can have total control
over how they do that.”
i’m sure you could still send presence sensitive notifications, although i don’t know if jabber watcher supports this since i haven’t had time to play with it yet.