There are rumors about this and google has the capability to have this data but I tried it and saw no magic results to prove that it is true.But if the domain is important for you (the theory comes from this point ) it is better to register it for more than one year.
I'd register for 3 years - if you're expecting to have the website anyways, you might as well, and it should have an effect on your serps.
I've come across a website about SEO and it says there that if you register your domain for a long time like ten years, Google will take good care of your website since Google appreciate that you take your website very seriously. This also make you think twice that you should not do any thing that Google doesn't like such as spamming because you know Google will put you in their sandbox and you will loose your precious domain that you have already registered for long. Try this technique. It's worth it!
Google knows that most spam sites are only registered for one year so that the owners don't have to pay that much money for them if they are no successful. I have heard speculations, but never seen any proof that it would have any effect on SE rankings.
People did speculate that this mattered, but it doesn't seem to, and Matt Cutts did a Webmaster Video earlier this year: http://www.youtube.com/watch?v=DnfM_szmDh0 In which he said that although there was a patent in place that considered domain registration length as a factor in ranking, Google do not consider this as part of their ranking algorithm.
I don't think it makes any difference for Google if you register a new domain for 1 year or for 5 years. what Google wants most is high quality content - registering a domain for more than 1 year in advance, doesn't mean that you will provide higher quality content.
Well domain age does matter for SEO, newer domains are more likely to get sandboxed by Google than older domains if you try to build too many links in one go. So a domain older than a year is generally good.