The logo should will be on the game hub screen (http://lazyreviewzzz.com/wp-content/uploads/2010/12/windows-phone-7-Games-hub-1280px-50p.jpg, like the icons on the far right without the XBOX Live tag), and we're pretty much open any concept.
The windows phone 7 developer solution comes with three placeholder images for all applications (attached)
- Large Tile Icon
- Small Tile Icon
- Loading Page