Google Earth April Fools
Google are usually quite inventive with their April Fools Day jokes. Last year they managed to add a cartoon image of some aliens holding a barbecue at the infamous Area 51 in America (images here).
This year Google produced a couple of fake products, GMail Paper (snail mail web 2.0) and Google TiSP (a free home wireless network utilising sewer pipes).
The best Google Earth related April Fool this year came from Google Sightseeing, which provided this kml link, purportedly to new live satellite imagery on Google Earth. However in reality the kml file overlays the image of a cloud over the earth so you can't see anything at all.