This is the current state of the little planet I have - sorry for the jerky camera - I was just in free fly mode recording with fraps (fraps.com)
This movie shows the quad tree planet that is procedurally generated with simplex noise (only 4 or 5 octaves) and the quad tree is 5 levels deep. Obviously I'm not going for a earth sized planet though it would be nice if the code could do that.
Lots of areas that need improving including fixing the atmosphere shader so you don't see stars in the day time, the water surface doesn't move (just bump map), lots of popping when approaching planet surface from space, obvious repeating textures, no underwater shader and all kinds of other stuff.
Still it's fun to show the progress of it.
Check out alexcpeterson.com for screenshot gallery and dev blog or just view the dev blog only at petrocket.blogspot.com (same blog on both sites)