I was about to register a co.cc domain. The question is that is co.cc domains are considered normal as .COM or other domains ?
If you type site:co.cc in google, you see they have over 11 million pages indexed. It has more indexed pages than all of blogger, twice as many as typepad, its not normal for a website to be allowed to index so many pages. I would say that google considers each of the "subdomains" on co.cc to be individual sites.
I believe it is like a blogspot.com, because it is a sub domain. If you buy a domain from them with only .cc, I think it will be equivalent to a .com or any other domain ending.
Other things to consider ... Everyone always talks about the benefits of having a network of websites that are hosted on different ip addresses. Who knows whether they do this or not, but the google patent includes being able to determine linking between the same ip address and if the domain name is owned by the same registrant, as grounds for devaluing/discounting links and not having them pass authority. When you sign up a co.cc, you get a domain you control (even though technically a subdomain, it looks like a TLD). The registrant information isn't yours. You can set up the domain at a free website host. The co.cc site recommends that you use Award Space to host your domain for free (you're allowed up to 2 domains for free) and they give you php, mysql, etc (actually you could use them without having to have a co.cc domain). Another thing is that there are so many awesome co.cc domains that are available for free. There are also tons of very high quality co.cc domains that are available for a low price. For instance, cars.co.cc is available and its only $67 a year, could you imagine what cars.net would cost? Nascar.co.cc is available for $9 a year. Something a little more obscure, like mybookblog.co.cc, is free. Those on a budget can set up a free co.cc domain, a free hosting domain, and have everything they need to start up a satellite site to promote their main website, for free. I use co.cc to snag high quality keyword subdomains that cost between $3 and $9 a year, but I think the boost you get from the domain exactly matching a query is worth it.
co.cc is not a domain. .cc is a domain. Google will treat your site as a subdomain. You will never have higher pagerank than the original domain.
Pagerank has absolutely nothing to do with subdomains vs root domain. You can have 1 page on your website that is PR8 and have a homepage that is PR1, you can have a subdomain of PR5 and PR0 on root domain. It all depends on who links to where and how your internal linking goes.