bit.ly is the default link shortening service used by Twitter and other social networking sites. The service will convert a link such as:http://www.sophos.com/pressoffice/news/articles/2009/11/01/bit.ly-agreement.html. The partnership with security vendors such as Sophos should offer an even higher level of protection in future. Its possible that cybercriminals might switch their focus to other less well-known URL shorteners when planting traps for unwary users.”]
Source: https://nakedsecurity.sophos.com/2009/12/01/sophos-bitly-making-short-links-safer/