Well, I now have the same symptoms as described in this discussion group. I'd put the CD in the superdrive for iTunes to burn, the computer accepts it, makes it's whirring noise (louder than a couple days ago), nothing comes on screen that says its able to read it, and around a minute or two it ejects the CD.
These larger 24inch iMacs are NOT the easiest to lug over to the Apple store, especially if taking mass transit! I have not found any solutions described here that works ...short of apple support.
I am a rather tidy and tech savvy person. No dirty CDs, no warped CDs, no inappropriate force to the drive, etc. Based on the number of similar postings, HAS APPLE ACKNOWLEDGED THIS AS A DRIVE DEFECT YET?