I have had the same problem. I upgraded from Snow leopard to ML and my dvd drive stopped working. I don't burn dvd's/cd's often so it took a month after the update to figure it out! I couldn't even read something on VM fusion! So i tried downgrading to snow leopard but that didn't work so i went all the way back down to Leopard, and then installed updates, and then installed snow leopard - my drive WAS working after i did all this. This leads me to believe it is a software issue and i for the love of god hope apple do something about this soon because i've had enough of their bugs so much so after this macbookpro dies i'm going to go back to windows!
So anyhow after this upgrade back to snow leopard i couldn't restore any of my time machine data because "my time machine backup was created on a newer OS" - ridiculous! So after a day of faffing around i had to upgrade to ML to get all my setting and stuff back and i restored it from time machine and have a drive that doesn't work again - back to square 1!
I've half a mind of flogging this crap machine on ebay and getting a cheapie £300 laptop from somewhere!
Apple if you see this please release an update so i can use my DVD 'superdrive' again please!
P.S. i've got a late 2008 macbookpro.