As covered in the general news, there have been quite a few attacks lately. The latest security breach comes from twitter were about 250,000 accounts were compromised to some extent.
Twitter has responded and as a precautionary security measure has reset passwords and revoked session tokens for these accounts.
For the full report please visit twitter’s blog post about this here.
As always, you should use a different password on each site you visit. To keep track of them all, use a password manager such as KeePass, or make life even easier with a utility like LastPass.