No, there is no app from the market that allows a non-rooted Thunderbolt owner to take screen shots (ShootMe and Drocap2 both require root access). However, there is a slightly more complicated workaround if you really want to get screen captures without rooting. I have tested it and it works (see my thread in the Thunderbolt Skins section for some examples), but it took me a minute to figure everything out and it can be kind of a hassle. Check out this link:
The article refers to the Droid X, but the process works on the TB similarly. Let me know if you have any problems and I will try to help you through it.
thnx for the info... with screen cap and wireless tether both needing root, i think root is the way im going. with the one click froyo 2.2 method, it seems it wont be to difficult, hopefully. dancedroid