One of the few things I remember about electrical engineering from my undergraduate education is the joke
Q: How do you build an amplifier?
A: Design an oscillator
Q: How do you build an oscillator?
A: Design an amplifier
This dichotomy is funny to those who’ve tried (and often failed) to build these electrical circuits. But it also underscores a similarity in the technologies involved, and points out that subtle changes in the design can produce radically different effects. It also works well as an analogy to (you guessed it) collaborative search. Social search based on recommendations, whether inferred from user behavior or from expressed through opinion, works like an amplifier: those signals (pages, documents, etc.) voted on by many people become featured more prominently (amplified) and thus are more likely to be retrieved.
Collaborative search, on the other hand, is more like an oscillator: the goal of the collaborating team is to find the possibly faint signal in the noise. The signal is faint because the information need may be complex and because exploratory search is by definition focused on discovery rather than on recovery. In exploratory search, people try to answer questions that have not yet been answered, rather than trying to find the same answer that someone else has already found. The collaborative exploratory search process is (to continue the metaphor) is like twiddling with the various knobs on the receiver to pick up faint signals from faraway places; social search is like morning radio.