You had surely already guessed this, being a sensible person with even a smidgen of awareness of how the video games industry works, but now it's confirmed: the PS3 and PS4 editions of Diablo 3 will not have cross-platform play with the PC original. It won't support a keyboard and mouse either, Blizzard says. Gosh, it's like it's a different game made specifically for consoles.
"While we think cross-platform play would be awesome, there are currently no plans to allow connectivity between PlayStation Network and Battle.net (this is pretty standard for most games that have PC and console support)," Blizzard community manager 'Vaeflare' replied on the D3 forums. "As a result, the characters on your Battle.net account and PlayStation account will also remain separate."
The PlayStation edition is a changed game, with features like an evade move. Throwing the two together, or adding a dodge to PC, would be weird, not to mention a huge investment of effort and money for a feature not many people will want to use.
It's being "designed with a controller in mind" on console, Vaeflare said, so don't expect support for USB mice or keyboards. Blizzard doesn't plan to carry controller support back over to PC either.
No word from Blizzard yet on when the PlayStation edition of Diablo 3 will launch.