SmartAlien and SmartAliens (owned by me)? I didn't read about domain name trademark and I registered SmartAliens.com, I found a similar domain name SmartAlien.com which is registered before me. Everyone can have "smart alien" as their domain name right? so this is not a trademark?
Trademark As it relates to domain names... a word, phrase or slogan used to identify and distinguish the source of the goods or services. Trademark law may be different worldwide. If someone registers a domain name such as microsoft.to then Microsoft would need to go to the courts in Tonga to fight to get the name back. Expensive international litigation is one reason why it is important to protect your trademarks before someone else registers the names. http://www.hostingconsumerreports.org/glossary.php The answer is, it depends. If the owners of that site find out they can sue you. You may be ok as long as your site and their site don't have anything to do with each other.
The url you gave for the other site redirects to another site. Registering a domain does not give you any trademark rights, it's the usage that establishes rights. Since it doesn't appear that they are using the name to identify good or services, they wouldn't have any trademark rights. If someone else is using the mark, and your usage is similar, then you could have problems - but don't worry about a domain registration that predates yours.