Posting on behalf of a reader.  You can check out my response on the blog.

Dear JobGals,

In recent months, the number of cold calls and emails from recruiters has been astounding.  The emailed inquiries are manageable as I can simply cut and paste a nice message informing the recruiter, that I'm currently employed, but may in the future be interested in other positions.  The phone calls are another story.  It's a little harder to return each call and sound sincerely grateful for the inquiry.  Since most of the phone calls originate from large staffing agencies, I've stopped returning the true cold calls, instead only responding with the thanks, no thanks to the smaller, true recruiting firms. 

This trend is of course, very satisfying given the rough ride for employees in the early aught years. I can say without a doubt, that the demand for mid to senior level developers is spurring this level of inquiry, more so than my own particular talents.  I'm also sure, that as tides do, there will come a time in few short years where the pendulum will swing back to favor employers. What concerns me is that in X-months time, I may need the services of these recruiters. So how does one best manage potential recruiter relationships without jeopardizing their current position or giving the recruiter the idea that you want them to actively pursue you as a candidate?

Thanks,
Jeff