What to expect.. Hmmm.. Hope I'm not the only one to respond.
Expect 1200 Disney pin traders. Expect 2 1/2 days of fun, trading, long lines to play games and get more pins, and more trading.
It is a blast. The event itself is held in a large indoor space in Epcot between Canada and England. You line up to get in at 9AM and they let you in around 930 IIRC.
The area is divided in three parts: An area to wait in lines to try and get new pins (you trade one of your pins - stock up on traders) for new pins that are recently released. Or you can decide NOT to wait in line, and bypass this section. In that area there are also event sponsors giving away their pins (one per customer). DLRP; World of Disney, HKDL; like that.
The middle area are chairs set up for the auction Saturday afternoon. That's a blast. And it can be very expensive. I am staring at the Eeyore prototype pin (one of two) that I won at the auction last year ("you paid HOW MUCH for one pin"?)
The far area of the space is devoted to pin trading. Dozens and dozens of long tables. You set up on one side, and you trade with people. From all over the world. Many of whom have know each other for years, and all of whom are looking for the next good trade. The pin trading is outstanding and I am really looking forward to it.
Before the event, you have a chance to enter a "lottery" to purchase new pins that come out just for the event. These pins can all be seen at
http://www.odpt.com; the lottery is called the RSP process, where you prioritize which pins you'd like to buy. In August, you get mail (we sit patiently waiting) with the list of what your've won in the lottery. You can then decide to keep (buy) it, or turn it back in. A bit complicated, but that is the RPS process.
There are also parting gifts distributed from late Saturday afternoon on.
It is a blast.