At the CodeRage III on-line virtual conference, I have done 4 sessions. 
For me, it was the first time speaking at conference done this way.
A few things were different:
- Sessions were 45 minutes presenting in stead of the normal 60 minutes
- The main body of the session was pre-recorded, the 15 minute Q&A was live
- I had to learn Camtasia
- The broadcasts were done through LiveMeeting
The Wiert Corner - irregular stream of stuff 