I had breakfast with a friend the other day. He's been writing some really cool iPhone apps and mentioned that he's wanting to focus for the future on apps that can be written and maintained cross-platform. He'll prefer to leave out the platform-specific "extra" functionality, he said, in order to be able to do the bulk of the work once and maximize the deployable surface area.

I got to thinking about this the rest of the day and came up with a whole list of questions for my friend. It's an interesting and logical approach, and certainly not wrong by any stretch of the means. Contrasted against the common move by devs to focus only on the iPhone platform for example, my friend's approach really makes me think. Now, to be clear, I have no idea what it takes to actually deploy an app to the iPhone and also have a version to deploy on Android or RIM devices, or on the upcoming Palm Pre (which looks really cool, by the way), or whatever. At least not without writing each one from scratch. My friend does, though. What I took from our conversation (as a business guy) was that it can be done at least to some extent, but that doing it in a cost-effective way means limiting functionality on any given platform. I may be oversimplifying, and in fact I probably am.

Then today I noticed that Mike Rowehl, who writes "This is Mobility," just posted an interesting article entitled "Please don't mistake my apathy for a lack of understanding," in which he takes on the recent meme suggesting that mobile developers are blindly leaving platforms other than Apple's behind, suck os Nokia's Ovi Store.

Which leads me to ask the obvious question: "What the heck is Nokia's Ovi Store?"

Granted, I'm not buying tons of mobile devices and deploying them like I used to, and certainly I'm not a mobile developer, but I'm still pretty well plugged-in (irony intended).

My past involvement in cross-platform development and porting of apps taught me that it's almost always a complicated and expensive endeavor. But it's not just building the app for the first time that one has to consider. Maintaining multiple platforms of the same app is can also be prohibitively expensive, unless there's a relatively simple and effective way to build once and deploy in many places/platforms. In the mobile world, it just isn't simple, cost effective and reliable enough (from what I can see).

And honestly, I want to choose the best devices and buy apps that take advantage of all the cool features those devices offer. I don't often want apps that leave out the latest hardware features and software enhancements.

Who's doing cross-platform mobile development and truly making it work? How are you doing it? If you've found the way, drop me a line - I'd like to hear about it.