A possibility to have a custom overlay for the full map that includes a draw method would solve the following difficulties I'm experiencing when porting from the Maps API v1:

- animation 
- when zooming in further than tiles are available, automatically enlarge the tiles of the zoom level above
- transparency

These things are not possible with the current API v2 implementation. 

Regarding the animation, I could theoretically use several TileOverlays that I make visible or not, but that would lead to flickering if one of the overlays is not yet fully loaded. In a custom overlay I would display an old tile as long as the new tile is not loaded.