There is no "official" documentation, and unless you're fully clued in to the Prototype way of doing things (apparently Rails gurus have an advantage), it can take a while to find your way around.
If you liked jordan's writeup, then read the entire source of prototype.js. I didn't understand half of it the first time through, but it was incredibly helpful to work through those bits and recognize patterns.
If you want a good review of important concepts, Particletree's Quick Guide should be on your list.
And finally, for a comprehensive reference to use while coding, tag Serio Pereira's Using Prototype.js 1.4.0.
By Chris Snyder on April 11, 2006 at 12:15am