Twitter announced on Friday February 1st they had been hacked in a sophisticated attack. Twitter said 250k accounts may be affected and have emailed those users. The stolen data included accounts, emails, addresses, and passwords. Whether or not Twitter contacted you it is probably a good idea to change your password, both for your Twitter account and for any other login that uses the same password. It is not a difficult matter to find more logins associated with the same email address, especially for popular services like Google, Facebook, etc.
Wired — Twitter Hacked