How to take emulator screenshots using Eclipse?
You can take a screenshot if you open the Android view "devices" (under Window --> Show View --> Other... --> Android --> Devices). Click on the device or emulator you want to take a screen shot of, then click the "Screen Capture" button (it looks like a little picture, and it should be next to a stop sign button). Occasionally the device won't immediately load the picture; sometimes you have to close/reopen the screen capture window.
This is equivalent to taking a picture via DDMS, but you can do it in Eclipse instead of opening another application.
Screenshots on Android Devices using Eclipse, a Visual Guide
In the DDMS perspective in Eclipse there is a "Screen Capture" button. (Make sure you have your Android SDK and Eclipse plugin up to date, not sure this was always an option). Just press that button and a screenshot of whatever device you have DDMS connected to (either a real Android device or the emulator) will be created and opened in a new window where you can save it as a png.