Well, an "official" event is called a trial, and dogs (and handlers) can be certified for the various levels of nosework (separated by degrees of difficulty, and scents used). The "Sniff 'n Go" follows the general format, but is more of an informal, social event (we had a potluck lunch!)
The info on the different levels and what all is involved in a trial can all be found at the official site,
http://www.nacsw.net/ (National Association of Canine Scent Work).