Google's I/O app for this year's event was released few days ago. It is a visual refresh to last year's corresponding app. Source code for this year's app is not yet available but it will be soon.
Last year's app's source code is here.
Source code of this app will be valuable for us developers once it is out. Few noteworthy features and nice details are the way action bar has this colored indicator right below it giving user's better visual guide where they are in the navigation structure.
I also like the way starred sessions are visually highlighted in the list. Catch notes are also integrated through Android intent APIs.
Nicely done Google and Roman. I hope the promise for source code holds!