I will try to describe the issue what happened to my friend. I do not want to say names, so i came up with the names below as an example. My friend is owning a website "c00lsiteshall" from 2006. Now a site "c00lsites" trademarked their website 2009. After that they kicked off my friend from facebook & myspace fanpage. And they threatened to sue my friend if all the content from the site that starts with "c00lsites" is not removed. Can this happen to everyone who will not trademark their website? I hope somebody will know more about this.
It's impossible to say with "example" names, but you don't trademark websites, rather names. Domain registration does not establish any trademark rights, usage (putting content on the site) does. The content/usage determines the "classification" of the trademark. So it depends on what both sites are about and who was using it for that purpose first. Just because they registered their mark in 2009, they could have been using it before (perhaps not even with a website) and you'll need to check the registration for their claimed date of first usage.
Also, remember that anyone can threaten to sue. That doesn't necessarily mean that they have any legal basis to do so. I have seen any number of cease and desist letters where the sender either (A) doesn't have a clue about the law or (B) knows exactly what they are doing and are simply bluffing. As mjewel indicated, there are a lot of other relevant facts that need to be known before anyone can draw any conclusion.