Now in its third year, Google's I/O developer conference offers a strong mobile focus--not surprising given Google's massive Android push.  And the developer community appears to be responding. According to the company, this year's I/O conference sold out more than two months in advance, making this year's crowd of 5,000 an exclusive bunch. FierceWireless Managing Editor Mike Dano is at the event. Take a look at his photo essay here.