Hoping to expand its monetizable online real estate, Time.com is seeking potential ad revenue sources on its Facebook, Twitter and YouTube pages.

The ad relationships come in the form of co-branded sponsorships. Siemens shall be the first to try what's been dubbed Time's "Stay Connected" program, which, among typical ad buys like banners on Time.com, will include placement on Time's social networking pages.

The only socnet that has made a formal revenue-sharing deal with Time is YouTube. But according to GM John Cantarella (via paidContent), "The impressions in this campaign are on Time.com and we are only giving the sponsor a presence on TIME's Facebook and Twitter pages—where it has 72,000 fans and about 1.4 million followers, respectively—as part of the overall campaign."

He also expressed hesitation about whether the socnet co-sponsorship effort would reap fruit right away. "We want to show how we can track users who come to Time.com from our Twitter and Facebook pages and how we can get advertisers' messages in front of those users," Cantarella explained. "They're not always the typical Time.com reader. These are in many cases a new audience for us and for the advertisers."

Integrations will be subtle at best, paidContent adds. "Sponsored by Seimens" appears in the background page of Time's Twitter site; on Facebook, photos of Time fans appear just above another Siemens sponsorship mention.

"The ads are being put in places where we ask users to take an action: fan us on Facebook, watch our videos on YouTube. They’re not just passively seeing a brand message. They’re much more engaged," Cantarella explained.

In terms of actual return-on-investment, Time believes its efforts will contribute to added prominence of its social media profiles and encourage Facebook and Twitter users to visit its own site more often.

Nielsen Online reports that monthly unique visitors to Time.com through 2009 have averaged about 7 million.