DimDim is open source Mozilla Public license and is a WebX like application that lets a presenter share his screen and client Aps over the web. All meeting participants have chat and voice. The presenter also has video. Its pretty cool.
The first steps for integration look pretty straight forward. We'd need code to allow a dotlrn-community admin to set up a meeting. Then create a calendar item to tell people when the meeting is and provide the urls to join a meeting. I think this is essentially what the current Moodle integration does.
Next steps might include making it easy to download and install both .LRN and DimDim, more security so a user can't get into a meeting just by having the right url, and making logs of the meeting content available and searchable through .LRN.
Let me know who is interesting and we can work together on this.