Disney has a website that has some of the basic information about Vinylmations at:
http://eventservices.disney.go.com/static/vinylmation/index.html
This is a pretty good place to see which sets are out and what the different Vinylmations look like.
The first Vinylmations (Park Series #1) came out in late 2008. Each set consists of 11 'revealed' figures and one 'chaser'. So a full set has 12 figures. If you buy a full box (24) of Vinylmations you'll get two of each of the 'revealed' and one chaser - the other figure will random from the 11 'revealed'. Otherwise, you can buy the boxes separately (I think they're $12 now). These are blind buys - you won't know which one you get until you open the box and at that point it's non-returnable/non-exchangeable. There are a few that you see before you buy - like the sports set and some of the special event ones. Otherwise, you won't know which of the 12 possible designs you're getting until after you've bought it. They come in two sizes: 3" and 9". The 9" are not traded and cost a lot more ($75 or so I think). The 3" are the ones that you see the most of and most commonly.
In the parks, at the resorts, and at DTD there are Vinylmation trading opportunities. Firstly, make sure you ask what the rules are at each place before initiating a trade. There are some places that are stricter than others. Mostly it has to do with the mystery box.
There are essentially two ways to trade: the mystery box and the clear box. For the mystery box, it's like another blind buy. Envision a black box with 24 (I've seen boxes with only 12 slots) slots. Each slot is given a number. You pick a number and trade for the Vinylmation that corresponds to that number - the catch is that you don't know what Vinylmation you'll be getting. I think the official rules state that you
must trade, but some locations/CM will let you keep yours if you don't like the one from the mystery box. Some places will also let you pick two numbers. If you opt to trade, then you get the one the CM showed you and yours goes into the mystery box for the next person!
The other type is trading is from the clear box. Usually there are three (but I've seen more) in a clear box that you can trade. As long as the one you have is not already in the clear box, you can trade.
All Vinylmations can be traded, except the ones that you make yourself. Long ago there was some questions about the clear/solid color ones, but on my last trip to WDW everywhere I asked said those were fine. While CM's often have mixed information, I take it to mean something when everyone says the same thing!
Have a lot of fun and remember to ask the rules before trading if you are worried about getting one you don't want.
Oh, yes, one other note. Usually when you trade, the little card is not included (nor is it required).
