Here is a link to the OSCON YouTube channel for 2011 video presentations. There are still two days of conference activities left, but there are currently 25 videos available to watch today.
Here is a link to the section of OSCON site that provides access to the 2011 live streaming keynote videos. They have also provided a nice schedule that lists the various speakers, their affiliations and topics that they will be discussing over the course of the entire week.
At some point in the future when the conference is over, I will hopefully be able to provide links to other interesting presentations given at this years conference as well.