Just a theory I posted on the thread.

I can understand it for the PS3 - Capcom will have to run and manage their own servers. Versus play will keep going and put more demand on said servers longer than coop will. If everybody bought their copy new, that'd be one thing as they could roll the cost into the game purchase. But I'd bet the $5 is pretty much due to used game sales - especially the $55 used copies being sold right next to the $60 new copies.

As for the 360? Well, used game theory still applies, but more for price-parity and "fairness in pricing" lest one version be unduly favored over the other.

Edit: Interesting - I don't think Gamespot covered the ~$26 price hike for the Wii in Great Britain.