Go the MBP page -> features -> click MBP 13in/15in banner -> scroll down. It talks about the Superdrive
Burn DVDs superfast.
Use the 8x SuperDrive on MacBook Pro to burn DVDs in no time. Since the SuperDrive writes to double-layer discs (DVDs with nearly 9GB of space), its great for backing up data, too.
If you try to buy the Retina MBP, they give you the option of buying an external SuperDrive. But if you try to buy a non-Retina MBP, there's no option to buy an external SuperDrive, so they would have to still have an internal SuperDrive.
I know - I'm not saying it isn't a logical step from Apple's side, but I still buy a lot of CDs and DVDs, so it would have been a welcomed feature in my book.
Buying a non-Retina Macbook would be just silly IMO.