Microsoft BUILD conference occurred in Anaheim, California from Sept. 13 to Sept 16, 2011. In this developer conference, Microsoft introduced Windows 8. How long did it take Microsoft to sell out? Two months. (http://www.electronista.com/articles/11/08/02/windows.8.focused.build.conference.now.sold.out/ and http://blogs.msdn.com/b/msdnmagazine/archive/2011/08/04/10192770.aspx)
Three months ago, Apple Worldwide Developers Conference (WWDC) 2011 ran from June 6 to June 10, 2011 in San Francisco. Steve Jobs introduced IOS 5 at this event. How long did it take to sell out? 10 hours. (http://blogs.computerworld.com/18047/apple_wwdc_2011_tickets_registration_sell_out)
Earlier this year, Google I/O 2011 from May 10 to May 11 also took place in San Francisco, California. The ticket to this developer event sold out in record time, not days, not hours but in minutes : 59 minutes. (http://techcrunch.com/2011/02/07/google-io-tickets-sell-out-in-59-minutes/)
Thus, we know which technology is most attractive to developer.