From Allearsnet -
2 Day/2 Park OR 3 Day/3 Park ticket - These are the tickets that were originally known as "bounce back" tickets when they first came out. You can only purchase the 2 day and 3 day passes at a WDW theme park ticket window, any Guest Relations location, any Guest Services location or at any Disney Resort front desk. You can not purchase them over the phone, at a Disney store, at any Disney off property ticket source, or online. These tickets allow entry to only ONE PARK per day. They do not need to be used at the same park both days. You cannot park hop with these tickets but you can leave and return to the same park the same day. Be sure to get a hand stamp before leaving.
2 Day/2 Park ticket - Adults $111.30 (includes tax) child, $87.86 (includes tax) expires 4 days from *purchase*. (3/04) You save $5 off the price of two single day tickets.
3 Day/3 Park ticket - Adults $164.28 (includes tax) Child, $129.13 (includes tax) expires 6 days from *purchase*. (3/04) You save $10 off the price of three single day tickets.
Hope this helps