The next 3 sections are all from the Google Earth Blog:
Google Geo Challenge Grants - Up to $100,000 - Here's the google.org GEO Challenge Grant post. I was recently thinking it would be a good idea for the X PRIZE Foundation to have a competition like their Crazy Green Idea for YouTube energy/environment videos, but using the Google Earth application to promote their X PRIZEs. Maybe this grant competition is a way for someone to do something similar (although the GEO Challenge Grants competition would be based on the idea and not for the ultimate result).
The Ultimate Where's Wally on Google Earth - Anyone who finds Wally's location on any individual day will be entered into a prize draw to win loads of Wally's merchandise. Anyone who finds all seven secret locations on Google Earth will then need to enter all the longitude and latitude references on the Borders website to get to the final round. The winner, drawn at random, will win a fantastic holiday to Wally's secret final destination.
Google Earth-based Virtual Alabama Wins GCN Award - GCN = Government Computer News
Winners of Panoramio Contest of July and August 2008 - This one is from the Panoramio blog. Pick a few images that strike you and see where on Earth they're from. Some of them seem to be from somewhere else altogether.