Well it works ina coupl eof ways. First, big names know each other. So they'll chat about candidates casually. For everyone else in the world its the holdiay season. For PDs, its match season. Remember its a verrrry small field. Second, if a PD or a letter writter calls on your behalf, that's very good. I have known docs to call and ask about a student and hear bad feedback and lose spots for it.
Do NOT take phone calls or letters of interest to heart. Yes its nice to hear but 1) few people get them 2) i know people who've got them, ranked the place #1..and failed to match there. Dont let it effect your rank list.
Which gets back to ROD's question: if they tell a couple they're ranking them highly 1) youll never know how many people heard this 2) you dont knwo where the student will rank them and 3) see above!
Most people wont discuss too much in detail because, well they just dont try to rip you apart in spite of what it may feel like at the time. Also, remember, PDs dont want to tip their hands too much either to other programs.
As an applicant you can talk to your peers of course. But I think this view of "retaliation" is way off. They're not out to get you. Rememebr they want happy residents and they're not looking to screw you.
S