I've been going from Lightroom to CS2 to do noise reduction (with the flexibility of layers and masks) and sharpening.
In Lightroom I've recently started experimenting with noise reduction on the adjustment brush (which can be plus or minus) to vary the amount of noise reduction applied to different areas. In terms of defining where the noise reduction gets applied, I find the adjustment brush easier and quicker to use than CS2 masks. As to exactly what type of noise reduction gets applied, Lightroom obviously doesn't have the sophistication of Noiseware, but for my part I don't really use those sophisticated facilities.
I have been doing some comparisons today using ISO 1600 images, which are fairly noisy on my camera, especially in shadow/background areas. The comparisons were between (a) using Lightroom for everything up to and including noise reduction, and then handing the image over to CS2 for output sharpening (I just can't get what I want out of Lightroom for output sharpening) versus (b) passing the image over to CS2 for noise reduction (apart from Lightroom's standard input (colour) noise reduction) and sharpening.
As I experiment more with Lightroom, I'm beginning to get results that seem to match what I can get with Noiseware. Don't know how far I can take this, and whether I will be able to dispense with Noiseware entirely, but I'm getting more out of Lightroom than I thought previously possible. Of course, for anyone who is making significant use of the more sophisticated facilities of Noiseware (or similar), then specialist noise reduction software will probably continue to be a necessity no matter how good you get with Lightroom's noise reduction.