According to a post by Graham Cluley on his Sophos blog, "the index page of that web site serves up obfuscated Java Script that loads a variety of pornographic adverts and contains a web form directed to a site called " A Twitter blog post confirming that accounts had been compromised, suggests that it's likely these are brute force attacks succeeding against user accounts with weak password.
Twitter says that they have reset the passwords for the compromised accounts, which should prevent any further spam messages from being sent by the attacker.
Earlier this year, an 18 year old US student, that goes by the handle ' GMZ', gained access to several accounts by using a brute force attack and made posts to users Twitter home pages.
Accounts that were compromised included Fox News, Britney Spears and Barack Obama.
My previous password at Twitter was 25 characters long (latest one is even longer & complex) and was full of Upper case alphabets, lower case alphabets, special characters, numerics etc(thoroughly jumbled as well).