We are looking for a chat solution as well. The current lead candidate appears to be 'Campfire' from 37signals.
- Campfire is a web-based group chat tool that lets you set up password-protected chat rooms. Invite a client, colleague, or vendor to chat. Link to a room on your intranet for internal communications. - web based, nothing to download or install - free for up to four chatters on-line simultaneously, various paid plans - iPhone, iPad, Android apps exist
Testing with the free trial will have to wait until after the holiday weekend.
It works with existing clients like gchat, etc. I've used this on 3 or 4 of my websites and it works really well. They also have a free version for one operator.