what's that font in the middle of the picture? i've seen if often, but never found out so far.

Yeah, it looks very pen-like, you're right. But actually it seems to be a font.
Here some more examples.

Look at the letters, they're all different. Of course you could have tons of alternates characters or ligatures, but that's highly unlikely. Just because we see something written on a computer screen doesn't make that a font.

If you're looking for something in the same spirit, you might want to take a look at these : http://www.dafont.com/hunglan-design.d674?text=Nothing+is+certain&psize=l