I attended the Kyoto Startup Weekend in 2011 and the London Education Startup Weekend in 2012. Between those two events, the focus of Startup Weekends apparently shifted from being about creating startups to teaching idea validation.
While this now makes the name of the event a little misleading I do think this is a very smart move indeed: in the Kyoto weekend the teams were all focussed on producing a great protoype/demo and wowing the judges. My team had a working prototype iPhone app to demo and we swept the majority of the prizes on offer. In the London weekend my team had an even more polished iPad app that amazed the judges but was absolutely not going to win any prizes because compared to the winning teams we had done comparatively little validation, i.e. pitching or demoing the concept to the people who would be the product or service’s actual customers and seeing how they react to it, and crucially if they would actually buy it were it to be completed.
Not all was lost; that prototype of ours was ready to be put in the hands of parents and kids (it was an educational app) so had we continued on we could have redeemed ourselves by doing just that and using the feedback to guide the development of the product.
I would wholeheartedly recommend attending a Startup Weekend if you have any aspirations at all to build a product or service of any kind; the energy of the weekend is infectious and there are always mentors on hand to give you advice. Personally I love the shift of focus away from creating startups and instead to validation as before the team leaders might have stressed about unimportant details (who’s on the team, how do I pay them, should I incorporate) rather than the more crucial point: is there a need/market for what you are proposing to build?
Startup Weekend Score = validation x (prototype + pitch)
You can get 10/10 for your prototype, 10/10 for a slick, professional pitch, but if you have zero for your validation don’t be surprised if you’re not one of the teams shortlisted for a prize. If you have a 4/10 prototype and a 6/10 pitch though (sounds achieveable, right?) but 10/10 for validation (pre-orders by the dozen!) then instead of scoring zero you’d be scoring 100 based on that simple formula I’ve come up with.
Despite being simplistic I think that really is the formula for success at a Startup Weekend, and by extension in your endeavours to build a product or service that people will actually want to pay for and use.
For a more detailed look at this I would recommend Rob Walling’s book Start Small, Stay Small  —it’s aimed at software developers but the principle applies everywhere: don’t invest serious time and money into building something until you’ve confirmed a real want/market for it out in the real world.