Also, I'd like to take a second to point out, that Portal 2 is NOT using the original Source engine as you so blatently claim. It's using the Orange Box engine (practically every game since the Orange Box has used the Orange engine), which by a general search turns up that the engine is only from 2007.
The Portal 2 engine is actually unique, built upon the enhancements of the AlienSwarm engine which in turn was built upon Left 4 Dead 2, which was built upon L4D, which was built upon Source 2007 (formerly the Orange Box engine.)
Whether you call it a 2011 engine or a 2001-2004 engine it still is impressive graphically in my opinion. I mean what else would they do?