I can’t even count how many times this issue has come up on DigitalPoint, SEOchat, and various other forums and blogs. “Does a domain’s extension or TLD carry any weight by search engines? Do they have a preference?”.
The answer: NO!
Why? If you think that Google or any other search engine would value a site higher simply because of the domain’s extension, then you need rethink how the internet works and what search engines like Google are suppose to do.
Google has a job, and that job is to provide its searchers the most relative and appropriate results for a certain keyword phrase. If your site has more quality content than all the other sites competing with you, you will naturally and organically rank higher than them (assuming no one is doing anything to screw the results).
Your domain’s extension has absolutely no relevance to its keyword position. As long as your site provides quality content exceeding all other site’s competing with you, your link building will take care of itself and your keyword rankings will climb higher and higher as your site builds more authority.