Congrats man, I only just got my PS3 last week and I love it.
I'd suggest inFamous. Sure it's not GOTY-league but it's a lot of fun if you like open world games. Also if you're in the mood for a racing game, between now and GT5, NFS: Shift is really good. Best NFS for a long time, if ever IMO. On the RPG side of things I hear very good things about Valkyria Chronicles and Eternal Sonata looks nice (I have yet to get either though). So you might want to check those out.
Personally I'm planing to get Uncharted (the first one before the second), MW2, Valkyria Chronicles, Flower, LittleBigPlanet, Echochrome, Killzone 2, R&C: A Crack in Time, Ninja Gaiden Sigma, Eternal Sonata and MGS4. As well as obviously upcoming stuff like GoW III, FFXIII, Last Guardian and GT5.
In other words, way more than I could possibly afford. XD