Agreed, access to iPlayer via dBox would be a wonderful feature! To the best of my knowledge, this is still being worked on.
It's not gonna be possible via the VM platform (although I get it fine on my subbed sammy 2110c) coz it's on NVOD, which relies on the red button / talkback. dbox2 doesn't do talkback, so that's a no-no...
But for a dbox2 that's permantly hooked-up to the net- it's feasible, in theory at least. Last I heard was that Auntie is encoding and encrypting as fast as she can, to stop access via the net route. So be patient, I'm sure it will arrive in some form.
TBH, I wouldn't mind paying a fiver a month to the beeb for a web portal for this stuff. And when it's hacked, I could cancel, LOL!