As an employer using Careers 2.0 profile search, I found it very useful. While I could mark and save profiles for the 'yes' profiles, I kept running into folks that I had previously mentally tagged as not a fit. I had to rely on paper, memory, or simply clicking the profile again and remembering why I had not contacted those people.
It would be useful to have a way to mark profiles as 'not a fit' or something to keep me from redundantly reviewing profiles.