Yes, the Steam screenshot key (F12 by default) will save a screenshot to your steam profile. You can then go into your Steam profile and make it public on your profile if you want.
Note that this overrides the AI War screenshot function, I had F12 bound to screenshot in the AI War options but Steam was intercepting it so I could only take Steam screenshots, I could not save a screenshot to disk via AI War. Went and rebound AI War's screenshot key to F11 to get around this.
I can't remember if F12 is AI war's default screenshot key or if I changed it, but just a heads up for you guys about this quirk.