Either Capcom devoted a whole shit load of people to working on the 3DS, or (more likely) Nintendo gave them a dev kit a lot sooner than the other 3rd parties. Probably a bit of both, but especially given how well the game came out and how it uses nearly all of the 3ds features to good effect (well besides tilt... but that doesn't count) we can almost guarantee that nintendo's strong relationship with Capcom is still there.
The simple fact is that most of the developers probably had about 4-6 months to get something out for launch hence why so many ports (rayman, SSSF4 though at least it got the professional treatment, bust-a-move, lego star wars III, asphalt, ridge racer) and near ports (madden, nintendogs, super monkey ball). Hell, just about the only thing not a port or near port was made by nintendo.
