You can have my site as an example for this. I have domain
http://www.adminforum.com/ and their is another site on the same niche as
http://www.adminforums.org with an s. How ever the site with an S came first, so it gets more higher ranking than me. But having not an S in my domain i also picked it really fast and if you now search for Admin Forum my site is on 4 or 5 position.
Basically, it has come to my attention that it is the content and activity that describes the ranking and not the domains. They do have a some worth in a users friendly way but not effects search engines much. As i am getting more and more members and topics. My rankings are going high. Everyday i get 10k- Alexa rank and have got to a lot less then before. I also got to the first page of google from 6th page.