You could implement this in the following way. 1. get all the follows of "techcrunch" 2. search for the keyword you want, saying "from: username1 OR username2 OR ... usernameN"
an example http://search.twitter.com/search?q=github+from%3Alebreeze+OR+matthewrudy shows all the tweets about github from myself and my friend Levent. Although with 32000 usernames I imagine it wont be fast, and you'd have to iterate over 320 requests to /statuses/followers.xml in order to grab all their usernames.
