Google has really ramped up the pace of updates to their satellite imagery in google maps and google earth. A few days ago, they launched updated imagery of Fresno and Clovis, taken on April, 25, 2011. Also added were no images for large parts of the state, including Los Angeles. Google has not announced the extent of the update.
Before that, the imagery was from 9/24/2009, but in mid 2010, Google uploaded aerial imagery taken sometime in early 2010 (before June). The aerial imagery is take by an airplane at an angle, so instead of just looking at rooftops, you get to see some facades and an idea of depth.