I just saw this in Yahoo answers..
In general, there are two ways to take screenshots on an Android phone: 1) root it and install a screen capture app and 2) connect to a computer and use the Android SDK. While both methods work just fine, they are overly complicated for something as simple as grabbing a screenshot. On the iPhone, for example, you simply press the home and power buttons at the same time.
Why Google didn't include an easy screenshot function in Android is baffling but as an HTC EVO 4G user, you don't have to worry about rooting or fumble with the SDK. It's unclear why this works on the EVO and not on other unrooted phones running Android 2.1, but for some reason, our favorite WiMAX phone is able to take screenshots with an app that usually requires root called ShootMe.
Here's how to do it:
Download and install ShootMe from Android Market.
Go to a screen that you want to capture.
Shake the EVO for about a second or yell at it (ridiculous methods, I agree, but that's the way it's done).
Retrieve your screenshots from the ShootMe folder on your microSD card.
Most Android phones require Root access and/or an app in order to be able to take a screenshot of your phone’s display. Well, that’s not the case on the HTC EVO Design 4G! HTC was kind enough to provide the ability to take a screenshot easily without any third-party software! You heard correctly… no root or third-party paid app required. This method is totally free and simple! Just follow the steps below to start taking screen shots on your HTC EVO Design 4G.
1. Hold down the POWER button and then press the HOME button.
2. That’s it! Seriously, it’s that easy! You’ll see a message appear on the screen that says “screenshot saved to Camera shots”. You can then go to your Gallery app to see the screenshots that you have captured.