I have downloaded the Windows 8 Developer Platform and have put together a list of things of why Android should fear Windows 8 when launched. Yes this is a load of competition thrown right into the OS tank. Android must be figuring out ever detail now because this was one great move by Microsoft.

1) Production vs. Consumption – Android (and iOS for that matter) are consumption vs production devices for the most part. Yes you can work on an iOS and an Android tablet but it is not that easy or appears made for that based on the apps that are out there. Windows 8 will be able to do both.
2) The last one if done right can win – It is like the PC metaphor he who has the highest spec PC last will win as the bar keeps moving up. A better example is Microsoft IE vs Netscape Browser Wars.
3) Partners / Distribution Network – Microsoft already has the largest hardware relationship/ network in the business with LG, HTC, Samsung , Dell, Acer, Sony, Lenovo and Nokia to mention a few. With Microsoft using partners for hardware vs Apple (and even Google with Motorola), that relationship for Microsoft is un- tarnished.
4) Plagiarism is the Greatest form of Flattery – iOS5 will show some aspects from Android, like message notification, expect this to be the same for Windows 8, coming into the game last offers a chance to observe your competitors, and then react accordingly
5) Convergence – Apple is moving towards an unified OS over the next few years, Android is going to try this with IceCream, but not on the desktop. Microsoft is going to do it with Windows 8, offering a similar look and feel for mobile, tablet, and desktop.
6) Easy Diverse Development- Writing apps for Windows 8, will be the easiest ever of any OS with developers able to choose from Java, C, VB, C++, HTML/CS5, XAML in 32bit, 64bit and ARM CPU API
7) Audience – 400million for Windows 8 the current number of PCs shipping each year currently.
8 ) Innovation- Not something you normally think of when you think Microsoft but they have already announced new hardware and support for USB3 (not Light peak yet), Touch screens on everything over 7”. Win8 work equally well with touch or keyboard and mouse. IE10 is also launching with Win8 and it works with Flash, addressing the ongoing issues with Android and iOS supporting it. Mihas already dove big into the cloud with Live, this carries on in Win8. The Samsung windows Slate PC given out at Build today is the first real device that shows off Win8 quite well.
9) No Fragmentation – Android with its good distribution early, but continued fragmentation is something Microsoft does not have to contend with. Outside of Androids control millions of generic devices are landing globally that will never get an ice cream update, nor will most Android mobile devices. Further what works in Win7 works in Win8.
10) Windows 8 Multi-screen background – Like WP7, iOS, and Android, this is a biggie as users can use the WP7 new Win8 UI but have dedicated old school apps on another page, this addresses easily all those with concerns on the new Metro UI.