To deter account hijacking, Yahoo has announced the availability of two-factor authentication for its Mail users. The feature, which can be enabled though the "Yahoo Account Information" page and is currently available for users in the United States, Canada, India, and the Philippines, requires a second form of verification beyond a password for any “suspicious” login attempt, the search giant announced in a blog post last week. Users would have to answer a security question or enter a verification code sent to their mobile phone. Presumably, such a capability would have protected former Alaska Gov. Sarah Palin's account from being compromised in 2008. In February, Google launched similar functionality for Gmail users, and Facebook followed suit in April.