I guess so, I've been using it to run Chrome just for the lolz and it works really well. Just add an app to your Steam library, then run it and good chances are that it'll actually start. Sometimes it doesn't but in most cases it works well!
I used to have a Firefox shortcut in my Steam games list so I could watch online video with the Steam overlay. It wasn't flawless, but it worked great most of the time, as long as I didn't try to open the overlay until I was in full screen.