What about the UEFI secure boot is messing up the PC ecosystem? You're referring to the widely-spread but extremely false rumor that secure boot is turned on, can't be turned off, and Microsoft has to approve any other OS you want to install?

Because that's not true. Secure boot is turned on, but for Windows 8 certification, it must be able to be disabled by the user. Microsoft is mandating that PC builders give you the option to disable secure boot. So I don't see how this is changing really anything. Maybe you can explain.

Last I heard any manufacturer of an ARM device capable of running Windows RT would be required to prevent the loading any other OSes via secure boot, or the disabling of secure boot.

But that's not messing up the PC ecosystem. PCs running Windows will be just like PCs running Windows always have been. Tablets and other ARM devices will be just like tablets and other ARM devices traditionally have been; the OS that comes preinstalled is the OS you have. You've really never been able to install, for example, Linux overtop of Windows on an ARM device before. The status quo isn't changing.

The only exception to the ARM rule in recent years has been Android, in a niche market, and only on some devices. That's not changing either.

> You've really never been able to install, for example, Linux overtop of Windows on an ARM device before.

Only because there's never been a port of Windows to ARM before.

If you want to claim locked-bootloader Windows RT devices represent a new class of hardware like, say, the Kindle, then I guess we'll have to see how they end up relating to the rest of the market.

OK, but that's not viable for everyone. The only applications where the vast majority of the userbase is going to have Server or Enterprise editions are business applications, and even then, to use your application, your customers have to manage expiring developer licenses on each of their machines. That's a lot of hurdles for the average application, where most of their customers don't have the right version of Windows and can't be expected to obtain and maintain a developer license.