You can hear the MIX10 Day 1 Keynote, featuring Scott Guthrie and Joe Belfiore, here: http://www.microsoft.com/presspass/events/mix/videoGallery.aspx.
And from the MIX site:
Once the keynotes end just keep watching as Channel 9 Live will begin streaming automatically until 5:30 PM, with interviews with Scott Guthrie, Joe Belfiore, Bill Buxton, Dean Hachamovich, Charlie Kindel, Albert Shum, Doug Purdy, Erik Meijer and many more. Follow or send questions to @ch9live on Twitter . You can view the full schedule here.
The MIX10 breakout sessions will be recorded and available online within 24 hours of the session. http://live.visitmix.com.