Twitter, Facebook and other social networking sites have risen from humble startup origins to redefine how 10s of millions of people communicate on a daily basis. Even the enterprise has started to embrace them as tools; Salesforce.com recently added Twitter to its Service Cloud, which already includes a Facebook application.

Now that the form has firmly established itself, though, how can Twitter and Facebook start to generate more substantial revenue? For years, investors have been pouring cash into social networking sites with amorphous sales plans on the hope that a profit-generating angle would eventually come to life (or else that Google would swoop in and snatch up their little startup).

Twitter may have found something of an answer this week. The site, which allows users to send 140-character microblogs, or "tweets," announced on March 23 the launch of a Microsoft-sponsored site called ExecTweets, which collects executives' microblogging missives for the public's reading pleasure.

Later in 2009, Twitter also plans on starting commercial accounts with expanded features for businesses at an as-yet-unspecified fee.

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