This thread reminds me of a peculiar job search story of my own experience: I went to a small conference in my field recently (about 150 people) and ran into two other postdoctoral researchers there, like myself, who were applying for jobs this year. I had met both before, but hadn't realized they were on the job market. Not too surprisingly, it turned out we were applying for basically the same jobs, although I was also applying somewhat more broadly than the other two.
Anyway, not too long after the meeting, I got a call for an on campus interview at one of the schools we had all applied to. Subsequently, I discovered this school had posted their seminar schedule, and these other two people are also being interviewed. (They had a total of some 200 applicants or so, so it was a bit surprising). So now I find myself in the peculiar position that two other people I know well are competing with me for the same job (well, actually, there may be two jobs). I like both very well and both are extremely well qualified (much more so than me, I think). So I'm not entirely sure how to feel about it.
Sorry to hijack the thread. Something pertaining to it:
Ways I have found out who was in the same campus pools as me or as a friend:
If the job is field specific those who are involved in the field, on field specific research fellowships or who have connections with other grads at other universities often heard. I had two friends from H-Grad in my sub-field on the market when I was---we traded whatever we heard: if I can't get the job, I hope you can!
In one place the schedule of "job talks" was on the bulletin board where they left me in the hall for 30 minutes. Reading the board for something to do informed me quite nicely. Didn't matter though because "Helpful New Prof" told me on the way to the airport. Why? I have no idea but I gladly listened to the info. (I think he was deeply unhappy and told me all sorts of interesting info actually)
At one interview the grad students asked me at lunch if I knew A and B. Yes, I know their names why? Oh...we heard them talk recently. (Really, why would two other abd candidates in my field be giving public talks...ah...)
I've heard stuff about searches in this way, too. I also get info back from random people who happen to know I'm looking -- for example, student X in my department meets postdoc Y at a conference; Y says he's interviewing at school A, to which student X also knows I've applied; student X reports back to me that Y has an interview at A. I'm pretty sure it wouldn't take a tremendous amount of snooping to figure out who was interviewing everywhere I've applied, but it's not worth the time, since the information is useless.
I had a graduate student ask a question at one of my job talks that was along the lines of the one you relate last there, only even funnier. He said, "We had a job candidate speak last week; I can't remember his name, but he said X. Do you think that's true?" That was a tough question. :)