How confusing can the advertising picture on Facebook get? You know all about General Motor’s $10 million pull-out last week. That move, and the dud underwhelming Facebook IPO, prompted WPP chief Martin Sorrell to declare on Friday that Facebook is “one of the most powerful branding mechanisms in the world, but it’s not an advertising mechanism.” Fast-forward to this week and WPP’s Group M ad-buying unit has struck an extensive licensing deal with Buddy Media to “make it easier for clients to spend money there.” Confused?

The traffic-driving impact of The Big 3 social networks – today, let’s rank them as Facebook, Twitter and Pinterest – is being constantly measured, calibrated, then re-measured and re-calibrated, it seems. This is important as marketers want to know on which networks it would be wisest to maintain a vibrant presence. The answer: all three. But it’s clear that one of these Big 3 is not just driving traffic, but big-ticket sales. Hint: it ends with “interest.”

As we write, the world is playing countdown to the biggest tech IPO in a decade. In a matter of hours, we’ll know how many billions (north of $100 billion) will add up to the value of Facebook. As we ponder all those zeros, here’s an interesting infographic on the 901 million-pound gorilla’s globe-spanning growth.

The two biggest stories in digital right now are Facebook… and Facebook. On the eve of an IPO that could value Facebook at $100 billion we get word that automotive giant General Motors is pulling its $10 million Facebook ad budget on account of diminished returns. Is GM telling us something, that Facebook is a waste of money as a marketing opportunity? The answer: not so fast.

Thousands of Facebook users have registered with organ donation programs after Facebook introduced an option that allows users to add their donor status to their timelines.

As scrapbook site Pinterest proves itself a formidable presence on the social commerce landscape, it’s little surprise retailers are taking steps to emulate the model’s success.

Engagement is the new currency for social marketing effectiveness, particularly for brands who are seeing renewed life on their Facebook fan pages ever since the new Timeline was introduced earlier this year. A new study out this week looks at which industry sectors are getting the most mileage (there’s one hint) out of their social engagement strategy.

Imagine the collective sigh of relief when Unilever’s skincare brand Dove launched a new campaign to banish aggrieving adverts and replace them with Dove-sponsored feel-good messages.

2012 is fast living up to its billing of being the year of Big Data. And it’s getting a bad rap from privacy experts. But does Big Data have to be bad? Here’s how it can be used to make business and society more sustainable.

Fitness label Reebok and social media measurement service PeerIndex have joined forces to reward Facebook and Twitter’s most influential sporty types.