Is there any chance of implementing the ability for programmers to leave feedback about employers registered on Careers 2.0, preferably anonymously and not shared with employers? 

While I would normally be against allowing anonymous feedback, I think it would be okay because of Careers 2.0's closed nature.

I'm asking this because I've recently been encountering a huge increase in all of the things that made Careers 2.0 better than job boards like Monster or Dice. 

For example, recruiters who contact everyone with some keyword on their CV regardless of whether they have the skills they're looking for (may as well equate it to spam), recruiters who contact you and then don't respond when you say you're interested (similar to the prior), and recruiters who fill the position while you're actively interviewing with them and just stop contacting you without letting you know. 

All of this behavior is a pretty big inconvenience to job searchers. I think some sort of functionality like this would at least give the employers more incentive to act professionally.