The vars defined hold the two array of strings, and the function generates the key. Calling the function with genKey(16, access_salt) will generate a 16 char random string from the defined array access_salt.
Pretty simple, really. Adds a new type of feed you can subscribe to. Simply add ?feed=json to anywhere you get a normal feed to get it in JSON form (but with a cutdown version of events).
Version 1.1 added support for JSONP. To get a JSONP response instead of a normal JSON structure, simply add jsonp=callbackName to your query, where callbackName is the name of the function to be wrapped with.