Every time you press the print screen key (whatever it's called or wherever it's located on your system), an unmucked image is saved to a folder on your computer.
I'm running Windows XP, and drive C is my primary drive, so the directory I'm going to give you is exactly where the images can be found on my system; you will need to modify the path based on the drive/partition configuration on your computer, and however your operating system names it's default program folder, or if you specified a custom directory during the installation of the game.
For me, my screenshots all go to: C:\Program Files\Cryptic Studios\Star Trek Online\Live\screenshots
I really hope this feature is kept throughout all of the patches. If any changes to it are made, it should be that the players are given an option to select a directory to save the screenshots to. I would love to just be able to press "print screen" and have the image without the HUD or other in-game labels, text, and so on be saved to my pictures folder so I could get to it quicker and easier, but it's no big deal. I am thrilled that I can press a button and have an image without all of the crap that litters the screen saved to a folder that I now know how to find.