It seems like today if you want to be cool, you throw a ™ or a Registered Trademark - ® - Symbol after your twitter profile, or after something you think is a cool name.
I feel it is important to state that these symbols are not things you should just throw around -- they are serious symbols that should be used correctly because they represent the law. Here's a great link from the U.S. Patent and Trademark Office: Trademark Basics
The ™symbol is a basic common law trademark symbol that you want to designate as a trademark.
The only time you can use the ® - (Registered trademark) symbol is once you have obtained a federal trademark registration from the U.S. Patent and Trademark office. This is a legal process that you can do yourself, or in our case here at RHD, we have a copyright lawyer who handles all of this for us. It is quite a lengthy process, I can say from experience. In our case here at RHD, it took us about 2 years to get both RHD and V8 Ranch as a registered trademark. During this time we were in high level of communication with the trademark office to complete the process. (See this link... Trademark Process)
Even if you have applied for a trademark and are in the process, it is illegal to use the ® symbol until you get the official designation from the U.S. Patent and Trademark office.
So to all you anonymous twitter users out there who have a catchy funny name and want to "trademark" it....be careful in how you do it. Make sure you do it the right way. Don't think that you can just slap a ® on something and it's yours forever -- in actuality, doing that is against the law.