Not that it’s a surprise, but its happening, at last. Apple’s iPhone is eroding the market share for Symbian, currently the dominant mobile platform operating system.

And it isn’t a minor slowdown either. This year Symbian enjoyed a growth rate of just 5%, as against the staggering  50 % annual growth last year. Folks at Nokia as well as the makers of BlackBerry, Research in Motion, have insisted that Apple’s entry into the smartphone market has only expanded the market, and that there is no real threat to them is now proving to be just some brave talk.

The smartphone market did grow well in the year, at about 35%, but Symbian’s sales only grew at 5%, suggesting that more and more people are buying non-Symbian smartphones. Contrast this with Apple claiming 27% of the US market in just one year.

And mind you, this is in spite of all the trouble Nokia has taken to buy out Symbian completely, and make it open source, and invite third-party developers to work on the platform.

But then, Symbian was slow to respond, I think. The iPhone has been around for more than a year, and Apple’s plans to make the iPhone a computing and multimedia platform rather than just a cool handset have been known for quite a while too. For all that, it took people quite a while to figure out exactly how disruptive the little gadget could be.

And the introspection regarding what they themselves were offering customers was long overdue by then. Still, when it came, it was reluctant, grudging, and more of a formality: Jens Schulte-Bockum, director of terminals for Vodafone Group PLC’s global marketing division, declared at Nokia’s World Developer’s Conference in December 2007:

We invited Apple into the market with a mediocre connective device because we overwhelmed users with complexity. We need to declutter.

Yep, you read that right. The iPhone is described as the “mediocre connective device”. The handset that sold a million units in three days when the 3G iPhone was launched. The device that everyone in the industry is now trying to copy, er, emulate.

With such hubris, It is no surprise that things did not move fast enough with Symbian. Even if they had, Apple was far ahead with its App Store launch, and the iPhone 3G launch, and the plans to release the smartphone in 70 countries.

I’m sure that, in the next few years, Symbian will improve a little while still steadily losing market share to Apple. But that battle won’t be very interesting. I’m more eager to see how Android fares against Symbian instead, both being open source.