Today I got around to implementing an idea I had for a while. I already had code in VandalSniper that would parse the IRC feed from browne.wikimedia.org into objects that represented each edit. So, I simply pulled out those pieces, and threw them in with two other libraries for accessing Jabber and MySQL, and the result is WatchlistBot, a Jabber bot that will send an IM to users when a page they've elected to watch is edited.
I think my total development time has been between three and four hours. The bot is live now; just send "help" to email@example.com for directions.