WebProNews

Only one website's buttons appear on Wall Street Journal stories, inviting readers to share articles, and those buttons belong to Digg. Although the highly anticipated shift of the Wall Street Journal from a subscription model to an ad-supported one hasn't happened yet, the venerable publication has deigned to dip its toe into social media.

Digg's Kevin Rose announced the good news on his blog. "The Wall Street Journal Online is adding Digg buttons across the entire site, and you’ll now have full (free) access to the articles submitted to Digg."

Don't look for the big yellow and blue Digg buttons that many sites carry. The Journal has opted for a subtler approach, displaying the familiar Digg icon and the text "Digg This" under the existing links to email or print an article.

That Digg button appears atop the whole reason the Journal, now run by media magnate Rupert Murdoch, has opted to allow the Digg masses to read articles for free. Advertising spots occupy that prime on-screen real estate.

If the Journal sells its ad space on an impression basis, which seems likely given their stature and place in the media, an onrush of thousands of Digg visitors will be a profit windfall every time a WSJ story hits the Digg front page.

Advertisers may blanch at seeing their bills increase this way. They are paying for a certain demographic: the well-compensated business professional, not a bunch of college students. We won't be surprised if WSJ advertisers ask to do their ads on a cost per action basis instead of CPM going forward.