In this post, we look at the ad opportunities on Twitter, Foursquare and Tumblr, beginning with Twitter that offers three different ad products. On Twitter, it’s possible to see some of the most popular topics at a given moment, and these trends are featured prominently next to a user’s timeline. The Promoted Account is featured in search results and within the  Who To Follow  section, which is Twitter’s account recommendation engine, identifying similar accounts and followers to help users discover new businesses, content and people on Twitter. Foursquare. Tumblr. MORE >>

Some would say that  Foursquare has blasted into the scene of location based social networking applications with a vengeance. From the Foursquare site: People use foursquare to “check-in”, which is a way of telling us your whereabouts. You’ll find that as your friends use foursquare to check-in, you’ll start learning more about the places they frequent. Just so we are clear… I have realized the full potential of Foursquare in my personal business and I have seen it being used across a multitude of different users… from power users to newbies. per point). MORE >>

Over at Fast Company, there’s a post about the American Express partnership with Foursquare. According to Fast Company, the AMEX/FourSquare deal  “…might finally give us some hard evidence as to whether social media is a worthwhile investment for merchants and marketers.&#. The book featured 40 authors, and over a six-month period Lauren used the social networks of the authors and the publisher to build awareness around the impending publication. Why the AMEX / Foursquare Deal Isn’t All That. American Express and Foursquare – So What? MORE >>

With Facebook’s recent roll-out of Places , many have posited the beginning of the end for what had been everyone’s LBS darling, Foursquare. After all, Facebook’s built-in user base of over 500 million people they could dwarf Foursquare’s user base of about 3 million with even a modest rate of adoption (about.6%.). As one middle-aged woman pointed out, she wasn’t going to use Foursquare on her iPhone because none of her friends were on it. With all that Facebook Places has going for it, how can Foursquare possibly compete? The Foursquare interface is a bit clunky. MORE >>

I read a great post a while ago from Jonathan Arehart on why he quit Foursquare and Gowalla. James goes into details about it here , but I think it does quickly translate into location based games like Foursquare and Gowalla: By checking into a location I am expressing my identity. So Foursquare now have promotions where, based on your location, a nearby service provider can tell you about their 10% off for Foursquare users or 25% off for Mayors, or whatever promotion they have. What future do you see for Foursquare, etc? Why Checkin? The Identity Issue. MORE >>