Although I like a tray, the solution is probably the same for both: unplug it and plug it back in. Also, if the tray were stuck, it's not like I'd take a screwdriver and pry it open - it's a problem either way.
I now have one of those new iMacs which does not come with an optical drive. Although I initially felt inconvenienced, I'm now seeing the advantages of this: if a disc gets stuck, all you're dealing with is a $40 optical drive, rather than having to open the whole computer. (I didn't buy an Apple SuperDrive; instead, I got a Samsung SE-218, which has been great.)