I have noticed a marked improvement for several domains that I have promoted long after we quit promoting them... they just keep rising. We created 3x as many backlinks as the competition but age of the site with no other work just kept it rising and rising after we quit promoting it.
In a live Webmaster Chat from October 22, 2008 found here: Q. Does having the domain name for a long period e.g. 5 or 10 years really affects SEO and give high rankings? A. Maile Ohye --Senior Support Engineer at Google-- responded that a site's reputation can be a indicator to search engines, but of course, it's not everything. Having a site for a long period of time can establish credibility with users, and as a search engine we also want to reflect this type of credibility. Of course, newer domains can also gain users and credibility. It seems like running a good site is a bit like running a reputable business. So yes, if your domain has been credible for years it can help. If you buy an old domain and put all your content on it in hopes of getting instant rankings, that's not the best idea.
if it has never expired and never changed its major properties (desing,html etc.) yes the older domain is VERY important for SEO lets call it not "domain" but older "website"