My phone is an HTC Sensation on Android 2.3.4, HTC Sense 3.0 and Software version 1.45.401.2. That a software update that came out in late August and early September. It's possible to take a screen shot without rooting your phone. It's just a little tricky; press power and
HTC, themselves, say this is possible and this makes it rare.
I think Android's lack of a screen shot mode harms it. If people wish to blog about apps then they'll likely need a screen shot. Why Android harm themselves when it comes to this by not providing easy access to screen shots is a mystery.
Here's the thing - this is so fiddly that I struggle to re-create it. I've managed to re-create it but don't ask me to do it on demand. I'll fail. Sometimes the phone goes into a mode when just pressing the home key takes a screen shot (which you deactivate by pressing power) but I've no idea how to get it into that mode. I think HTC could make some friends by being a little clearer here.