From the recent google io 2013 video presentations on YouTube it was announced the android google io application was to be made available via git. Most importantly this android application used ActionBarCompat. I have just downloaded iosched and its using ABS (ActionBarSherlock) have i got the wrong git url?
The I/O 2013 source isn't out yet. When it's out, it'll be here: https://code.google.com/p/iosched/. The current code you downloaded is the 2012 app which does indeed use ActionBarSherlock.
It's likely blocked by the fact that ActionBarCompat, Google's action bar compatibility shim, also isn't out yet.
If I were a betting man I'd bet you'll see them drop very close to each other. You can follow the Android development Twitter, Google+ Page, Blog, website, etc. to find out when it's out. It'll make quite a splash when it does, it will take significant effort to actually miss the announcement.