If you've been following along with Google I/O, you'll already know what the big announcements are. Android 'L' is probably the main thing, but there were plenty of other tidbits to work though. Which probably explains why it took almost 3 hours.
If you've got a spare lifetime to site and watch the keynote, it's available online. I'd at least recommend the Android, Wear and Fit stuff.
I've not made it all the way through yet!