Just got an email update from the electronic artist "Celldweller" today. The original entry on his site has been erased, but I still have the email confirming this:
"Celldweller's "Solaris" is being featured in the upcoming Microsoft racing game Forza 3. "Solaris" is also available on Soundtrack For The Voices In My Head Vol. 01."
Original link: http://www.celldweller.com/2009/05/filmtvvideo-game-surrogates.html
Hope I don't get you in trouble Celldweller
P.S. omg real music in Forza three I'm so excited Holy crap!