2007 could be called the year of the mobile operating system. Since Microsoft entered the scene around five years ago, the smartphone operating system industry has been fairly stable. Symbian, Linux, Research in Motion, and Windows Mobile make up the bulk of smartphone software, each to varying degrees of success in different regions.

But in 2007, Apple introduced the iPhone, which runs its own brand of software, and Google announced that next year its Android mobile operating system platform will come out.

The entrance of two new operating systems from well-known brands shakes up the plans of some mobile operators, creates some headaches for end-users, presents bigger challenges for application developers, and indicates some fundamental changes in the mobile industry.

To put the discussion in perspective, realize that smartphones make up a relatively small portion of overall mobile phone sales. In 2006, 8 percent of phones sold were smartphones, said Chris Hazelton, an analyst with IDC. That's set to grow in 2007, but will likely hit only the low double digits, he said.

Why all the interest then? The industry has high hopes that existing phone owners, who now make up a large part of the overall population in developed countries, will want to move on to the next generation of more capable smartphones.

In addition, operators are gradually indicating that they're stepping aside from their role as gatekeeper and will allow more outside companies to offer phones and services to their customers, opening up new opportunities for software, hardware, and Web services companies.

Verizon and AT&T have recently made bold statements indicating that they're opening up their networks to more devices. While end-users might have the option to use a wider variety of devices, Verizon's announcement at least comes with a catch. "It's like, 'OK, we'll bow to what you want, but be careful what you wish for. You can bring these phones to our network, but if you have problems, don't call us'," said Hazelton. Verizon hasn't promised technical support for handsets that run on its network as part of its new open program.

Still, at the very least mobile customers in general will soon be able to add the iPhone and new Android phones to the list of handsets they can choose from. That's good and bad for phone customers. "End-users will probably need to do a bunch more homework," said Scott Horn, general manager of Microsoft's mobile communications business. That's because they'll need to figure out if the new software can support the features and services they want.