This week's need-to-know social-media news.

Pinterest, the company whose trademark social pinboard allows users to display images they find appealing, has decided it's time to work toward profitability. "A lot of last year was keeping up with growth [and] the big change with touch-screen devices," founder Ben Silbermann said. "[This year], we're building foundations to monetize." What are it's plans? Pinterest is getting ready to introduce paid advertising. And it is studying how Pinterest users convert into online shoppers, so that it can eventually take a percentage of brands' sales revenue.

Pinterest has enjoyed explosive growth over the past year, with total user visits to its website increasing to 48 million last December, up from 9 million the previous December. In the same period, Pinterest's staff grew from 20 to 100. Pinterest has raised $140 million in venture capital so far, and might seek more -- at a $2.5 billion valuation. -- Wall Street Journal

Twitter now more searchable.
If you've noticed a change in the search function of your Twitter mobile app, you're not alone. The social network has changed search so that user accounts to follow and relevant tweets now appear together in search results. Previously, users had to decide in advance which type of results they would like to see. The change not only helps users, it also opens up more search inventory against which Twitter can sell Promoted Tweets -- its most effective ad product for generating clickthroughs. -- Business Insider

Tumblr adds real-time notifications.
Tumblr became a little bit more like Facebook recently when it began rolling out real-time notifications to its dashboard. The look of it should be familiar to many users -- it resembles Facebook's sidebar ticker that shows the minute-by-minute activity of friends and pages you've liked. The new Tumblr dashboard could be a way to further connect users with each other, though you can disable the live updates if you don't care for them. -- TechCrunch

Twitter gets into TV analytics.
Twitter made its largest acquisition when it purchased social TV analytics firm Bluefin Labs this week. Bluefin provides analysis for brands, advertising agencies and TV networks, enabling them to track social engagement with TV shows and ad spots, and use this information to drive future activity. This could be the biggest move yet in Twitter's efforts to increase revenue through relationships with other media companies, especially in TV. -- VentureBeat and CNET

Facebook users are getting tired -- of Facebook.
The world's No. 1 social network isn't usually shy when it comes to bragging about its staggering number of active monthly users. But a new survey finds that 61 percent of Facebook users in the U.S. admitted to voluntarily taking a break from the site, some for several weeks. One major reason: "the general sentiment that Facebook was a major waste of time." When building a startup, think about engaging customers and users over the long-term. If a founder isn't careful, today's hot upstart can be tomorrow's boring giant. -- The New York Times