I've been doing some thinking into this and these are the ways I see it can be done. One way is to split the HDMI from the PS3, with one going to the tv and another to some sort of dongle. This dongle would then stream the PS3 picture in a similar way to a Remote Desktop connection to the iPad, for which some sort of app would need to be written. This is definitely possible for the iPad, but I believe the HDMI from the PS3 is encoded in some way to stop people recording it (I think, I might be wrong), so it may not work from that side of things.
The other way is to use the remote play feature built into the PS3. This allows users to control the PS3 over a network, which is basically what I want to do. The problem with this is that it only works with PSPs and computers, so it is not compatible with the iPad. You would probably be able to get around this, but my skill set is not at that level.
That's as far as ive gotten. Let me know if you have any other ideas.