Inactive Twitter accounts could soon mean that you will loose your username if you do not update your account or at least sign in every 6 months.They will then put the username back up for grabs. This could be very interesting for many of us SEO's out there. If this policy is released, Users that claim the dormant names will have the option to registrar their new username. 

Twitter’s policy say's that if an account is in active for more than 6 months, you will loose your username making it available again. So I suggest that you get tweeting again before you lose your username. I would also like to say that I think this year is going to be even more important to use social media in SEO.

A Spokesman for Twitter has announced that they are thinking of adding this to their policy there is no official date yet.