We have just launched a group messaging capability for SharePoint that enables teams to communicate in real-time from within Team Sites.
We already have a number of companies embedding it into their SharePoint environment and a number of partners interested in offering it to their clients.
This is free to try and I would be interested in people's view.
If you are interested in taking a closer look either let me know in this thread or alternatively you can find details here:
I look forward to hearing from you.