How many iPhone app developers can Microsoft buy? by Philip Elmer-DeWitt @FortuneMagazine April 6, 2012, 11:46 AM EDT E-mail Tweet Facebook Google Plus Linkedin Share icons The secret to populating an unpopular smartphone platform: cash incentives Rovio is making Angry Birds Space for Windows Phone A nice piece of reporting by Jenna Wortham and Nick Wingfield landed on the front page of the New York Times Business section Friday morning, two days before the launch of the Nokia Lumia 900. When free phones and promises of prime real estate on the Windows Phone app store wasn’t enough to get reluctant developers to write software for the new device — the first fruit of a collaboration between Microsoft MSFT and Nokia NOK — Microsoft reportedly starting writing checks to cover some of the cost of development, which can run anywhere from $60,000 to $600,000. Among the developers that, according to the Times, have been paid to write for the Windows Phone OS: Foursquare, creator of Foursquare Cheezburger Network, creator of I Can Has Cheezburger? and (reading between the lines) Rovio, maker of Angry Birds By the time the Lumia 900 is released, the Times reports, the Windows Phone app store will have more than 70,000 titles, including Netflix, YouTube, the Weather Channel, Amazon Kindle and Fruit Ninjas. Still missing: Pandora, Instagram and all the Zynga games. “We are by no means satisfied with our catalog,” Casey McGee, senior marketing manager for Windows Phone, told the Times. “That’s something we can get better at, and do better at, every day.” At last count, Apple AAPL had more than 600,000 apps and Google’s GOOG Android nearly 400,000.