With the arrival of the most recent batch of Android phones, particularly the Motorola Droid and the Google/HTC Nexus One, Android has become a real contender in the mobile device space. As a result, the market now has four major platforms for developers to target.
Android is open source but relatively new; the iPhone has a huge installation base, but the App Store is crowded, and it's been difficult for developers to cooperate with Apple. BlackBerry is still the enterprise device of choice. Although from what I can tell, Windows Mobile is definitely the easiest to develop against with the best toolset out there. Let us know which mobile development platform is most appealing to you.
Also, when I asked Programming and Development readers back in October 2008 if you're developing on mobile platforms, 53% of you said that you are. In order for us to get a current snapshot of how many of you are developing on mobile platforms, please take the following poll.
Justin James is the Lead Architect for Conigent.