Now that Microsoft has debuted its Windows Phone operating system on Nokia handsets, the complete platform could put real pressure on Apple and Android. Since the Nokia world unveiling Oct. 25, much has been written about the unique designs of the phones themselves. But how do the guts of those stylish Nokia handsets stack up? Of course, the Windows Phone OS is a new ecosystem altogether compared to iOS and Android, but with the latest update 7.5 (Mango) we can kick off the mobile OS war between the three.

The Windows Phone OS has access to Microsoft Office built right in, something iOS nor Android has. It remains to be seen how much effect that has on consumer users, but it should have an effect on enterprise users more directly. This is one factor that Microsoft's new OS can employ to break Google and Apple's hold on the mobile OS market.

Prior to Mango, Microsoft had little success in the mobile market. Windows Phone OS was struggling to account for even ten per cent of the smartphone market. Obviously, Microsoft is betting that Mango will not just be a fringe operating system compared to Google's Android and Apple's iOS.

Google, on the other hand, released the Galaxy Nexus smartphone with the Android 4.0 OS in Hong Kong Oct. 19, and 4.0 features the science-fiction like Beam transfer service. It allows two Android 4.0 phones with the near field communications chip to wirelessly transfer music and photos. Android 4.0 also includes a new widget system allowing users to store their favorite apps in folders, and a new, clearer Roboto type face. With iOS 5 mobile users get over 200 new features from its predecessor, not all of which are minor. iOS 5 features the company's chat-like iMessage, full Twitter integration, Wi-Fi sync and photo editing.

For now, the Nokia phones that came out Oct. 25 will not be available in the U.S., and Android 4.0 won't debut until the Galaxy Nexus goes on sale in a couple weeks. But for those holiday shoppers who want to know exactly what these operating systems can do, this should be a good start.

Tell us in the comments if you think iOS 5 can withstand the challenge from Android 4.0 and Windows Phone 7.5.