You can consider registering the name of your company on social networking site because this is your trademark or other called it "branding". If you notice most especially on facebook we some of our friends and acquintances or even us are normally searching our favourite brands. Then, share it to twitter etc.
When, registering to social media you have to think the way consumers think because your "Username or Trademark- it is your best asset. But of course, it depend on what is your target market.