Gamasutra, executive producer Wilson (we are going to assume it is Matt Wilson) said that Sony Online Entertainment is still considering cross-platform play for their MMO The Agency, seemingly contradicting statements made earlier to Eurogamer by lead designer Hal Milton.
But if you read each of the original source articles, both Milton and Wilson states that it is entirely possible technologically to have cross-platform play. They even have very similar reservations; console certification process hampering updates and gameplay balance issues stemming from differences between PC mouse/keyboard and the PS3's controls. We are guessing SOE simply haven't finalized their plans yet.
Either way though, it was revealed that at least the game accounts will be both global and cross-compatible -- meaning that if you have a PS3 account, you can still play at a friend's house on their PC with your own account and vice versa. We'll keep you updated if there are any developments.