Twitter admitted in its own research a few weeks back that the typical user has to view a hashtag at least four or five times “before it really clicks.” The message was clear to Promoted Tweets advertisers: ratchet up the Tweets if you want to be seen. Is Facebook any more effective?

As the Sun reminds us today: celebs are hot for Twitter and Facebook. Lady Gaga, Justin Bieber and Stephen Fry have massive fan/follower bases that hang on their every Tweet and update, a potential bonanza for brands with Twitter-savvy celeb spokespeople. Ah, but not so fast. New rules in the UK designed to protect the public from the celebrity-endorsed Tweet could impact this practice before it gets a chance to take off.

Google has unveiled overnight a series of upgrades to its now two-year-old project to make its search results more personal social. Starting today, you’ll see item like your colleague’s Tweets and your friend’s Facebook “like” recommendations interspersed in the search results.

Last week, we got a 2010 report card on the Web-based side of the digital economy. Today comScore releases its mobile year-in-review, and it is a completely different story this time around with Asia clobbering us here in the West with an overwhelming majority using their handsets every day to take part in the social web, download content and make purchases via mobile wallets.

After reading in today’s Wall Street Journal that private investors are valuing gaming developer Zynga at between $8 billion and $10 billion, and then this beaut in the New York Times – that JP Morgan is looking to raise up to $750 million for a social media investment fund – I figured it’s now time to get out a scrap of paper and compare the present, pre-IPO multiples as we know them for the next batch of Nasdaq darlings. The numbers remind me of another heady period a dozen years ago.

Facebook unveiled yesterday a much-needed revamp of Pages that give admins the flexibility, and, more importantly, visibility to interact with the social web in the name of the fanpage they represent. Here’s what it should mean for all you admins flying the flag for multiple fanpages.

2010 was a good year for e-commerce and online advertising, and a great year for Facebook and Twitter. It was another rough year for Yahoo, AOL and email. ComScore delivers its 2010 U.S. Digital Year in Review report, packed with interesting data points that we’ll quickly summarize here.

What did the online public think of Groupon’s $3 million Super Bowl spot? A wacky laugher or potentially reputation-damaging gamble? Maybe this poll of polls will clarify.

That’s the big conclusion drawn from the 2011 Edelman Trust Barometer, the details of which were revealed yesterday at the WEF forum in Davos. And where do our friends and peers rank? They are losing ground. Fast.

We’ve chronicled here many times the impressive success Greenpeace has had in using the most public of social media forums to denounce environmentally destructive corporate practices by brands ranging from Nestle to Burger King and force them into a public about-face. Fast Company this week looks back at one of Greenpeace’s first major social media pressure campaigns – the Kimberly-Clark “Kleercut” initiative – in a tale that all companies would be wise to heed.