Apparently there's a dongle now out for the 3DS called Gateway 3DS, as the 3DS has been hacked.
http://www.modchipsdirect.com/gateway-3ds.html
http://www.youtube.com/watch?&v=uW3LxuDvHeI )
Don't have one yet, was never interested. Bought a DSi for my girlfriend 2 years ago, using a DS TWO dongle, which works pretty well, but she used it twice during that time, like me too. Perhaps I could sell it, and get a 3DS instead. I tested the DS TWO dongle on a 3DS, and that also works just fine.
EDIT: I just now bought a 3DS, a white one, looks really cool, and it was only 150€ on Amazon (brand new). I know that there's a guy here at work who desperately wants a DSi with all the games, and as my DSi is almost new, and I own the whole set of almost 7.000 games, and plus he's a super moron, I'm gonna sell him the DSi with the games for the same price.