Very interesting.
Cross-platform support is becoming increasingly common for PlayStation games, with many new releases for PS3 and Vita being cross-buy (pay once and get both games) and cross-play; in fact, Dragon's Crown launched without cross-play, but just got it added in the most recent patch in Japan. It also already exists in at least one Wii U/3DS game, Monster Hunter 3 Ultimate.
It's the sort of feature I would love to see catch on with more developers. Up until the past couple of years, the most we had heard about it was a couple of Xbox 360/PC games that supported cross-platform play earlier in the generation, but now we're constantly getting cross-buy and cross-play PSN releases from various indie devs. I'd love to see more releases from bigger devs with cross-platform play, especially with the upcoming userbase split; instead of everything being PS3, 360, maybe Wii U, and PC, everything's going to be PS3, 360, maybe Wii U, PS4, Xbone, and PC, and cross-platform multiplayer would help with the smaller playerbases this will lead to in the short term, even if it's only really viable for games that use dedicated servers.