BACKTYPE http://www.backtype.com got my attention recently at Ycombinator. Their idea is to spider on the commenter's web URL(s). Thus in theory their approach is more universal across blogs than either IntenseDebate or Disqus. In practice it will depend on how extensively their spider pulls in content. Go see if their search engine has picked up your posts, then "claim" them under your profile.

I believe the only sites that currently access the full Twitter XMPP firehose are: Zappos, FriendFeed and Twittervision. (Please update me with any corrections.)

There is a nice mash-up http://www.monitter.com which will follow three keywords with optional geo parameter. Wish those parameters could be part of their URL stem. Latency is part and parcel though...