Yes, there's noise in the deep shadows for the 30D. The same is true for my 300D. If details are too dark for the exposure you've set, there's always going to be some noise visible where it lacks detail (noise reduction software such as Neatimage will resolve this problem for the most part). It's nothing to worry about, as long as you expose as brightly as you can without losing too much highlight detail, then make a linear conversion with a negative exp comp and/or highlight recovery. A more subjective approach works for me: using the LCD, several shots, and exposure compensation, rather than using the histogram. Some people swear by the histogram (expose to the right), but I prefer my own method. I prefer working with pictures, and getting to know my camera rather than looking at histograms while I'm out in the field.
However, noise in the deep shadows for ISO 100 and 200 will be significantly better than higher ISOs, but this should be obvious to you.
