WDW Disability Pass and Information
The information is updated as of October 2015, with one exception...there is no longer a physical pass, it is linked to your Magic Band.  All guests linked to you need to have their Magic Bands scanned as well to make sure they can enter rides with you.  Instead of handing them a physical pass, you'll just scan your Magic Band at your chosen rides.  Only the person with the disability needs to scan for the return time.

Disney is very disability friendly.  If you have a disability, including a non apparent one, go to Guest Services at the first park you go to and request a disability pass.  They will not require any proof.  They'll ask your name, take a photograph of you with an ipad, and have you sign the pass.

Go to the standby or the fast pass line at the start of each ride, and hand them your pass.  They'll fill out a return time based on the current line wait, and stamp it.  You can then return to ride walking through the fast pass line at the return time. Unlike fast pass, the time doesn't expire in an hour, you can use it the rest of the day, but you cannot get another ride scheduled until you have the first ride crossed off.

Just to be clear, you can only have one ride scheduled at a time.  Once you've completed that ride, you are free to get another.