Ok, well I'm one of a few people on these boards to have gone through this process, so here it is:
Jacob's Comprehensive Guide to the Winter Pool
Firstly, if you have made it the pool, then well done. This means that whichever college you applied to thinks you're at the academic standard of someone they would happily give an offer to, but they just have too many people at your level, and they'll be trying to find you a place at another college. Usually somewhere between 1/5 and 1/4 of the people placed in the pool will get an offer.
The way the pool works (at least in small subjects like music), is that there is a meeting at which there are profiles of all the pooled candidates - these include your personal statement, your SAQ thingy, or whatever it's called, your submitted work, any test that you did at your first interview/interviews, and some sort of report on your first interview/interviews. From here, DoSes will look through the profiles and pick out people who they think would be the best students. They then either make straight offers, or do another set of interviews sometime in January. This decision is rather idiosyncratic to each DoS, and in effect gives rather random timing to the process. I think that more academics like to reinterview to see who they would prefer teaching for three years.
There are two slightly strange things that may happen during the pool. Firstly, you may be given an offer by the college you first applied to. This is more likely to happen with the more undersubscribed colleges, but I think it happens everywhere. If this happens then well done, I doubt they'll want you back for a second interview (given the awkwardness and the fact that they've already interviewed you). he other thing that can happen is that you can be pooled to more than one college. This means that you'll have another two sets of interviews. Mostly when this happens, they'll try and have the interviews on the same day, or have you stay up overnight and have the interviews on consecutive days. This is rather stressful to say the least, but it does appear to be a good sign, and will give you a good chance to show your off academic skills.
A further possibility is that you will be pooled to what snobs refer to as 'lesser' colleges. These are either newer colleges, single sex colleges, mature colleges, far away colleges. What one has to deal with is the fact that there is no such thing as a 'bad' cambridge college. In fact, they tend to differ rather less than most students would have you believe. Yes, Robinson isn't as beautiful as Trinity great court, but the chances of you living in trinity great court as an undergrad are pretty small anyway. Yes, Girton is an extra 15 minutes cycle ride away, but Cambridge is the only place in the world where 15 minutes cycling is viewed by the populous as a terrible plight. Wherever you go, you get an equivalent education. Wherever you go, you'll make friends, and you'll have teaching by world experts in the field.
In terms of hearing from the pool, you will normally receive a phone call, so keep your mobiles turned on. Try not to give up hope. Some colleges will contact you later than others, so the fact that a freind has been 'fished' out of the pool doesn't mean that you may hear a week or two later.
Remember to take pool interviews just as seriously as your original interview. Chances are you'll find it quite a bit easier having already gone through the process of being interviewed. To an extent you'll know more of what to expect, and how to answer questions. Make sure you know your PS and your written work if you do get a pool interview.
Being pooled is a reflection of your ability. You are all excellent students and even if you don't get an offer, the chances are that you'll do exceptionally well wherever you go. You are not to forget that. Keep up with the learning and the banter.
Jacob (MB)