With Google maps, you can toggle between a map view and a satellite image view. To view satellite images of MLB parks, click the links below, then click on the satellite link in the upper right corner.
A couple of pictures (Milwaukee, Cincinnati) are only low resolution images. A couple (Philadelphia, San Diego) show the ballpark under construction. The Marlins' home looks like it's configured for a bowl game, while Anaheim seems to be set up for some kind of dirt bike race or something.