The question of domain name registration and its impact on SEO is not a new one. However, every so often, the question comes up. Would it be better to register your domain name for 5 years instead of renewing it for just another year?
In our past coverage, we reported that there are some signals sent by extended domain name registrations, including informing the search engines that your website is not spammy (you're here to stay). Google does weigh in on these signals, apparently (albeit not as much as other factors, obviously).
Domain name registration lengths may also show more about your commitment to your work. If you extend your registration for many years, it shows that you're serious about your business. I'd say that this is stronger than renewing it yearly every single year.
Others disagree that domain name registration lengths have any profound impact on SEO. Instead, the older the domain is (rather than the length of registration), the better it is.
Forum discussion continues at WebmasterWorld.
Update: It seems Google has gone on the record saying domain registration length does not impact rankings.