RIM twice hosted a Port-a-Thon event to get developers engaged and working on porting their apps to the upcoming platform. Devs were given $100 for any app that was approved in BlackBerry’s app catalog.
In addition, BlackBerry gave away devices with the first developers having two to five apps submitted getting a PlayBook and those who had more than five getting a BlackBerry 10 Dev Alpha phone.
RIM will fight a tough and uphill battle against Windows Phone, and most notably Android and iOS, but 15,000 apps are certainly a good start.
source: BlackBerry via The Verge