The screenshots in the normal game work almost the same as in Oblivion. You edit the INI to allow you to take screenshots, and then use the Print Screen key.
Unfortunately, this does not work if you are using MGE (like I very obviously am).
In MGE, the screenshot function is bound to a key macro. In order to set it, launch the MGE UI, open the macro editor, select a key, and in the two drop boxes that are not grayed out, select "Function" and "Take Screenshot."
I've bound the function to the ] key, myself.
By the way, if you think you are seeing 3D water in those shots, you are not mistaken.

*seething about Oblivion's horrible water*
This post has been edited by Thomas Kaira: Mar 8 2011, 08:44 PM