Here's an unexciting story: Street Fighter X Tekken will have DLC.
Now that we got that out of the way, here's the much more interesting story: Street Fighter X Tekken's DLC will be cross-platform across the PlayStation Vita and PS3. "As long as you're using the same PSN account, things you've purchased on the Vita version will work on PS3 and vice versa," Capcom producer Yoshinori Ono said.
"Yes, they're different hardware, but they're part of the same PlayStation family, so to speak, so we're already talking with Sony about ways to sync things together," Ono told Joystiq.
Sony has been relatively lax with its DRM, and has allowed single purchases to be transferred across multiple devices. For example, PlayStation Minis, PSone Classics, and video rentals and purchases from the PlayStation Store can be used on PS3 and PSP with a single purchase. It appears that Vita will follow, allowing DLC to be purchased once for multiple devices.
The ability to sync DLC between the Vita and PS3 opens up some other exciting possibilities. Would Sony and its third party partners consider allowing entire games to be synced around both platforms? That would make "transfarring" a lot more palpable--if instead of buying two games, you could simply buy one to use across both devices.