Capcom mainly discussed its side of the conflict, which will be called Street Fighter X Tekken. That's "Street Fighter Cross Tekken" if you're saying it out loud, sort of like Namco X Capcom, the crossover RPG that Namco released on the PS2. The upcoming fighter will be a two-on-two tag battle game, and so far Ryu and Chun-Li are confirmed for the SF side while Kazuya Mishima and Nina Williams are set on the Tekken side. Dan also makes an appearance in the trailer, but that's not exactly confirmation that he'll appear in playable form. Capcom's game will run on the same engine technology that powered Super Street Fighter IV.
Namco will also develop and release a crossover fighter. If naming conventions hold, this game will probably end up going by Tekken X Street Fighter. That's how Capcom and SNK handled it when they did a similar character swap for Capcom vs. SNK and SNK vs. Capcom. But all of that is unconfirmed at the moment and no actual details on this game are available.
I was a serious Tekken fan early on, but once Tekken 4 hit, that and the subsequent sequels felt like they were quickly losing their way. But the characters themselves are solid, so I'm at least interested to see what Capcom does with them. I'm... a bit less interested in seeing what Namco's developers do with the Capcom characters.
Street Fighter X Tekken is in development for the PlayStation 3 and Xbox 360, but no release date has been given at this time. Here's the game's first trailer.