Thanks for all the comments.
OmeNu, I got the toon shader from a tutorial I found on the web:
Its done in Mental Ray, using contour shaders. Its actually quite simple. Check out the scene I've attched (which is from the website). Look at the shading network...its very easy to use. I can set it up now in minutes. This is just a basic one though, I'm sure that you can get it looking even better by messing around with the settings a bit more.