In addition to the year-to-date data already provided, and Gartners analysis forward through 2012 already provided, add these stats which cover the six months from Sep 2009 through Feb 2010:
As for where developers will be going next year, consider:
Im Abandoning iPhone Development. Mobile Orchard To Stop Publication.
70% of iPhone developers heading to Android, says AdMob
Android catches up to iPhone in dev interest as iPad cools
Android Market app count surges 68% in March
You just can't have abusive relationships with developers and not expect some blowback.