Using a Cyber Gadget CodeFreak game capture utility, one YouTube user has found the 3DS will run backed-up games and even homebrew applications. In the videos past the break, you can see it using the Game & Watch Collection
to launch unsigned code, including a copied version of Mario Kart DS
and the Lameboy emulator
Additionally, it would seem the R4
cart also yielded results on the 3DS. Another YouTube user has discovered that right now the 3DS will played backed-up games from an R4, since it recognizes it as a DS cartridge. Of course, Nintendo could kill compatibility at any time through a system update.