The Macbook Pro 13", with 9400, also runs Star Trek Online in bootcamp, just fine. It doesn't beat todays dedicated graphics cards, but from my experience, it is definitely the next best thing if the ones with the dedicated cards are out of your price range.
It works very well for most important graphic heavy tasks, but not quite ready to take on the latest games with high graphic settings on. That's what the dedicated cards are for. Still, it really helps that you have 4GB in there. The card mainly slows down when you lack a good open resource of ram for the card to do its work. 2GB seems nice, but there are a few things out there for which the amount of ram used severely hurts your performance unless you add 2 more to that ram. (One good example. Neverwinter Nights 2)
Now in comparison to most of the previous integrated cards, it would seem to run like a dedicated card, but it isn't. When faced against stuff like the 9600, or even the 8800GT or above, it doesn't quite compete on their levels for games. However, there are other graphical performance things, outside of all those render engines games use, for which it handles its own on.
Probably has a lot to do with when you have spare ram for which the card can use, unhindered, and the fact that the whole system architecture now utilizes DDR3 speeds (which was the memory advantage of previous dedicated cards). The fact that it is still an Nvidia, with much of the latest bells and whistles, and drivers (eg. not Intel graphics).
