In 2010, I think the Apple iPhone will face some serious competition against Google's Android smartphones. HTC and Motorola have come out with some really nice Android smartphones. Google has the Nexus One. HTC has some nice new models launching in 2010.
As a result, you have many hardware options if you choose Android. If you want a thin touch-screen phone, you've got that in the HTC Droid Eris, the T-Mobile myTouch, or the HTC Hero. If you want a hardware QWERTY keyboard, you can get that with the Motorola Droid or some of the newer HTC smartphones.
Apple will always have a loyal base of users, but many non-Mac users will easily make the switch from iPhone to Android if they don't need to switch wireless carriers and if they have Windows-based PCs at home and at work. I know that many physicians love their Macs, but they're stuck with Windows-based PCs at work to run their Electronic Health Records (EHRs) or Electronic Medical Records (EMRs). Right now, several EHR vendors have developed iPhone apps for their system, but it's only a matter of time before we see some Android solutions as well.
Android will be used on mobile devices beyond the smartphone, so it will quickly become a ubiquitous mobile operating system. Apple may come out with a tablet running the iPhone OS, but that won't compete against all the laptops and mini computers that may be running Android as a complimentary OS. 2010 should be a very interesting year for Android and iPhone.