Windows Phone 8.1 represents developers' best chance to make some money - at least as far as Microsoft is concerned. The company released a developer preview of Windows Phone 8.1 today and hopes that code writers will get to work creating compelling apps and games for its refreshed mobile operating system.

Microsoft explains that the new OS isn't for everyone. "The Preview program was created to give developers time to test their apps, and to validate that their apps run as expected on a real phone before an operating system update is made generally available to your customers," said the company. This line is to be expected and is more or less the point of most developer programs. Want to try it out? There are several different ways to gain access to the OS.

Microsoft prefers app writers to officially register as a Windows Phone Developer. This carries a nominal $19 fee, but allows developers to publish apps in the WIndows Phone App Store when all is said and done. If you're not interested in paying the fee, you can also choose to register as a developer with App Studio. This is free and lets developers take advantage of online tools to create apps that will run on their own devices. Last, device owners can choose to download the developer tools to register and unlock their phone.

As always, there are risks involved in downloading operating systems in preview form. Microsoft warns that installing Windows Phone 8.1 Developer Preview may void the manufacturer's warranty, as well as the warranty of the mobile network operators. This means if the code breaks the phone, you might be left with an expensive paperweight. Further, the developer preview only includes updated code from Microsoft. Remember that the OS has essentially three layers involved: Microsoft's, the manufacturer's, and the carrier's. The preview only offers Microsoft's bits, which means it may or may not function properly with the existing on-device OEM and carrier code. Last - and this is a biggie - once a phone is updated to a new version of Windows Phone it <i>cannot<i> be reverted to an earlier build of the OS. In other words, you'll be stuck in the developer preview until the final version of Windows Phone 8.1 is available.

Perhaps the most interesting aspect of Windows Phone 8.1 is the addition of Cortana, Microsoft's personal assistant. Cortana will learn user behaviors over time and eventually begin to automate some tasks, such as managing travel and scheduling. Windows Phone includes a number of updated APIs, as well, which developers can put to use in new and interesting ways. Windows Phone 8.1 also introduces the idea of universal apps, which will be able to run on Windows Phone, Windows RT, and Windows 8.1. In other words, code once, and run on all Microsoft's mobile devices.

Want more info? Microsoft offers tons of resources here.