Train Defense passed review on the first pass in only a couple of days. Apple seems to be doing a great job with the review process lately.
Of course, I immediately found an exploit that lets a good play pretty much play indefinitely (or until he makes a bad mistake).
So Update V1.1 has been submitted which features a new Air Artillery Unit as well a FlameThrowers.
FlameThrowers are a lot of fun. You can set fire to enemies and they slowly burn down their hitpoints until they explode. Of course, Freeze ray will put out fires so you if you intend to mix Fire and Ice, you will need to be strategic with your placements.