Criteria for a platform from which to build a collaborative IM service

open source
- existing user/developer community
- stable
- has an option for anonymous patrons on the web (no account required)
- XMPP/Jabber-based
- reporting and statistics tools not only tied to a built-in module
- archives transcripts
- generally extensible
- routes sessions to different agents depending on some criteria

Potential features that are desired but probably don't exist that we should expect to be able to build

- connects to commercial IM networks
- co-browsing
- web interface elegantly degrades to something that works in a screen reader