Using the Android SDK from the command line, I can get a list of the running devices available using:
The Eclipse plugin does it by connecting to the emulator via tcp/ip. To connect, (for linux), type
~/code$ telnet localhost 5554
Connected to localhost.
Escape character is '^]'.
Android Console: type 'help' for a list of commands
Replace "5554" with whatever number comes after the hyphen when you type "adb devices" - "emulator-5554", for instance, would have telnet port 5554 open.
Then, type "avd name", hit enter, and you should see something similar to the following:
In this example the emulator's name was "GB10".