A couple of Japanese giants are already jumping on the bandwagon.
After Nintendo let the cat out of the bag, announcing the Nintendo DS, people started to wonder if anyone other than Nintendo would develop games for it. According to Japan's Nikkei Keizai Shimbun, we now know that there will be at least two more companies making games for the mystery system.
Konami and Namco have both said that they will create software for the Nintendo DS, though any sort of specific details weren't given. Naturally, since the system was just recently revealed to the public, it would be likely that other developers didn't know about it until not too long ago, and therefore very unlikely that any sort of games are in development.
As more developers pledge DS support, we'll be sure to let you know right away.