You buy a "package" that includes parking, an entry ticket and two autograph tickets. One autograph ticket is pre-assigned but you don't find out who it is for until an hour before the event actually starts. The second autograph ticket gets traded in when the ticket windows open. In years past there were four lines. Each line ends at a set of ticket windows where you exchange your ticket(s) for a player/coach that is assigned to that group of windows. When you get in line you have no idea what players/coaches will be available to that line. When you get to the window you can only exchange 1 ticket per player/coach. For example, you buy 2 packages and have 2 exchange tickets and you are lucky enough to have guessed right and gotten in Cliff Lee's line. When you get to the window you can only exchange for one Cliff Lee ticket. There are also players that will not be available for autographs because they are in the photograph booth. These tickets are purchased seperately online when you buy the packages.
Once the gates open you get to watch the VIPs on the field with all the players while the lines form all around the stadium. Staff will be handing out the layout while you are waiting in the exchange line so you'll have an idea of where you want to go. Eventually the players and coaches make their way to the autograph stations and photo booths. There will be one "star" or two players/coaches at each station. Once the graphing starts you wait in line, get your graph (1 per) and race to the next line. In the past when some of the lines for the non-stars start to dwindle you can make cash donations to get additional graphs. For stars and slow signers their lines remain long and they may never get to the cash option.
They also have grab bags for $20 where you give 'em $20 and they hand you a bag which can have just about anything in it from SGA's to autographed hats, autgraphed balls, etc. There are games for kids to play and get prizes; there is a live auction at the end that you have to register for to participate.
It's a good time but remember it's a fundraiser for the Phillies. To them it's about making $$ not making sure that everybody gets as many autographs as they want.
For more information do a search on here for Phestival and you'll see some experiences from the last couple years.
One final note - last year I compiled a spreadsheet with everybody's wants with cell phone numbers. You can bring it with you and as soon as you know what guys are available to your line you may be in a position to trade tickets. Last year everybody really wanted the same players - Howard, Rollins, Utley, Ruiz...... Since a bunch of folks have completed or have almost completed their 2008 WS projects I think their may be more opportunity for trading this year. I'll do it again and if it helps, great! If not you'll at least have contact information and meet some of us down there.