Rovio announced on Twitter today that Angry Birds Space racked up 10 million downloads in less than 3 days. Unfortunately Rovio didn't give more details as to which 3 days saw more than 10 million downloads (presumably it was the first 3 days after launch) or which platforms were proving most popular. Angry Birds Space (the latest game in the Angry Birds series) launched on March 22nd (Thursday last week) on to the iOS, Android, Mac and PC platforms.
Nevertheless, it is a very impressive feat that Rovio was able to garner so many downloads in such a short period of time - it's clear to me that Angry Birds continues to be an incredibly powerful brand that is being managed very well by the folks at Rovio. It's also worth pointing out that last November Rovio revealed that the Angry Birds series had been downloaded over 500 million times since launching in late 2009.