Lest you forget, 2010 is the year of the mobile device. It’s a subject I blogged earlier this month, and it’s a subject I’m returning to now in order to add further clarity.

That first blog on mobile delusions tackled the thorny issue of return on investment (ROI). In that posting, I suggested that busineses must think carefully before rushing head first into mobile development.

Well thought-out business plans, I suggested, will always win in the long run. That statement remains as true as ever; in fact, its resonance has increased as the proliferation of different smart phones continues to rise.

If you’re asked to think about handheld devices, it’s more than likely you’ll think of one specific phone and operating platform. That selection might be pushed by your personal preference for a BlackBerry or Nexus One, but the vast majority of people will immediately think of an Apple iPhone.

Why is the iPhone so all consuming? Consumer and media hype certainly helps: you don’t see national TV news coverage of people queuing round the block to get hold of a new BlackBerry device. For Apple, every new device is a national – no, global – event (see earlier blog on the iPad).

Apple has been smart. It’s beautifully designed gadgets appeal to a ‘fanboy’ mentality, where the ‘Twittering’ elite will have you believe that each new Apple device is representative of a new era of social and technical development.

To be fair, some of Apple’s devices are great. The iPod helped make digital music a portable reality. It’s continual development through the iPhone showed how openness can spawn great application development.

But the iPhone is just one device in an increasingly crowded marketplace. According to analyst Gartner, Apple’s iPhone represents just under 15% of the global smart phone operating system market.

The proportion, although significant, lags well behind Research in Motion and Symbian, the latter of which still accounts for almost half of the smart phone market. The conclusion is simple: developers will have to look beyond the Apple ‘fanboy’.

An app designed for an iPhone should be easily portable across all mobile operating systems. Considerable market fragmentation means an app that has limited appeal for one group might be more attractive on another platform, particularly for BlackBerry users that desire enterprise interactivity.

Which brings me back to the difficulties of getting an ROI from mobile development. Fragmentation and differentiation means you need to be learning about how you can make mobile pay.

And the best way to create an ROI is through web-based apps that can easily cross platforms, rather than platform-specific software.