According to this 1UP story, redesigned versions of Brain Age and Brain Age 2 will be the first downloadable games available for DSi via the DSi Shop. The news comes from this morning’s Nintendo Media Summit in San Francisco. From the piece:
Fils-Aime confirmed that after downloading a game for your DS from the Nintendo DSi Shop, it will be available on your flash drive for playing at any time. Presumably DSi owners will be able to redownload titles at no extra charge if they delete them to clear space, as with the Virtual Console.
No dates. More through the link.