For android

1: there are several screenshot applications in the market, AND if you have gingerbread, you don't need root permissions.
Some of the apps only require you to shake your phone in order to take the SS.
2: my favourite way is to use ddms (which comes with the android SDK)
Go to developer.android.com, download the sdk, install it as per the instructions on the site, and fire it up.
Select your device, then screen capture from the menu and there you go. ;]
Be sure to download and install the adb usb drivers though, otherwise windows won't recognise the adb bridge. Linux users should be fine without additional tinkering with the system.
Note for linux: when you uncompress the sdk in a particular directory, make sure you add it to $PATH.
for ddms to work, you NEED to have adb running (server). Just run it once with "adb shell" and it should be fine, until you restart.
If anyone needs to be walked through these instructions, PM me.