what’s the other button aside from F3 key to save the render?. i am using imac and its F3 key was assigned to Exposé function.
A way is to open the UV/Image Editor, now using the scrolling menu (just to the right of the menu View and Image) select the “render result” at this point do Image->Save or Alt-S.
If you’re not too attached to the F3 key for Exposé, you can change it or disable it in System Preferences. Personally, I prefer the corners of the screen for screen saver activation, as well as some of the Exposé controls.