1GB does most of what anyone does well. 2GB is heavy users. Beyond that is bragging rights. That's TODAY!!!
Yes, I did some benchmarks on video rendering with 512M, 1GB, 2GB and the payoff beyond 1GB was all of 5 minutes on a 6 hour job. So don't look to big gains past 2GB.
Bob
I'm a webmaster currently running a PowerBook G4 (1.67GHz with 2GB RAM). I'm going to upgrade very soon, but need the best for all the applications I'm running. I use CS3, usually with at least 4 of the apps running simultaneously, plus Firefox, Entourage, and iChat. I will also be adding Final Cut Studio to the mix.
Will the MBP with 4GB RAM be enough or should I go for the Mac Pro where upgrades and more RAM are possible? Also, is anyone running those same programs on a MBP? Any issues?
Thanx!

Chowhound
Comic Vine
GameFAQs
GameSpot
Giant Bomb
TechRepublic