Digit said it, not me. :-)
Regarding the new Quick Selection tool in Photoshop CS3, Digit Magazine out of the U.K. had this to say...
"The new Quick Selection tool enables you to create an selection area by 'painting' areas to keep and ignore, with Photoshop selecting surrounding blocks of similar colours automatically. It’s a massive improvement on the old Magic Wand, but it’s not as accurate as plug-ins such as OnOne Mask Pro or Vertus Fluid Mask - and lacks those tools fine-tuning controls for dealing with tricky areas such as hair."
Like anything else, there are always different ways to tackle the challenge of making a good selection. Sometimes the best way is with a standard Photoshop tool or technique and I agree with Digit that the new Quick Selection tool is a nice improvement over the Magic Wand - and I'm sure I'll use it from time to time - but again, every image is different and as such there are times when you'll want more control over your selection and you'll find that a plug-in like Mask Pro is better suited for your needs.