There's a great commentary over at tnmc.org  about what got cut from the STAR TREK movie - including George Kirk, the cut Nero-Klingon plot and some other stuff. There's also a look at what Shatner's cameo might have been if he'd been approached.

Personally, I think it's a good job it was ditched. Shatner singing? Awesome.

Kirk singing? Not so much.

I think a lot of the rest of this was filmed - specifically the Nero-Klingon thing - so hopefully we'll see this show up on the DVD.