business model for socialnetworking sites

An article on nytimes.com about business models: twitter and yammer. It's basically saying twitter is having problems and trying hard to find a business model after already gained popularity, while yammer is rather small but started with a business model, which is a paid one dollar per user model focusing on company users. 

It's argument is: under current economic environment, scale is might not be the most important thing because popularity does not guarantee revenue. Not to mention popularity is hard to get. Here's the quote at the end of the story:

“Now it doesn’t matter if you want scale first because you just can’t have it,” said Paul Kedrosky, a senior fellow at the Kauffman Foundation. “You have the luxury of being able to decide between small and focused on revenues or large when you have capital. When there isn’t money, there’s no choice.”