[Update] PlayDead CEO and co-founder, Dino Patti, has confirmed to Joystiq that this news is indeed true: Limbo will be coming to both Steam and PlayStation Network "very soon".
[Update 2] @PlayStation Twitter has confirmed a July release date for Limbo on PSN. That is very soon.
There's no denying that Danish indie developer, Playdead, had a hit on their hands with Limbo. But sales could have been better, if only it were available on more platforms. Playdead was asked if they'd ever consider porting Limbo over to the PlayStation Network, to which they replied: "We're open to everything."
If a new rating on the Korean Game Ratings Board is to be believed, that's exactly what is happening. A rating for Limbo has been discovered, with Sony Computer Entertainment of Korea as the publisher. Here in the States, the original publisher was Microsoft Game Studios. If this is indeed true and Limbo is coming to PSN, we would expect SCEA to serve as publisher.
PS3-only owners take note - Limbo is a fine example of video games as art and could very well be the best downloadable title available to date on any platform.