Pretty interesting article coming out of the CES:
Apps call, but will your phone answer? - CES 2010- msnbc.com
"The Nexus One will run on version 2.1 of Android, and the Droid soon will. But other popular Android phones are stuck on version 1.6, which doesnít run many apps written for the newer releases. And many apps written for version 1.6 canít run on version 1.5, which is still prominent in the Android market."