Up until 3.0 they did. I spent a few days trying to get the PS3 to recognize the iPhone as a bluetooth device using 3.0 APIs. I was unsuccessful though.
To have an app that works with Bluetooth the pairing device must be part of the "Made For iPod" program. So unless Sony gets the PS3 approved in that program you cannot write an app that will pair with the PS3 to be used as a remote.