You might remember that we've talked about 'secure boot' and UEFI before, in relation to Windows 8 PCs. Microsoft is making UEFI mandatory on Windows 8 PCs (replacing the aged BIOS), and that 'secure boot' must be enabled. According to Microsoft this make PCs safer. As a side-effect is also means that users can't install another operating system onto their PC without first disabling the 'secure boot' option. Microsoft has said that OEMs are free to offer customers the ability to disable this feature on x86 and x64 PCs.
That was PCs, but Microsoft has now said that ARM devices will get a different treatment. Here the 'secure boot' switch will be locked and customers will be stuck with using Windows 8.
Why would Microsoft do such a thing? Well, several reasons spring to mind, both good and evil.
Protecting users from themselves
ARM devices might look like normal Windows devices but they're not. Locking the UEFI reduces the temptation for people to tinker with and mess with the system.
Someone at Microsoft just decided it should be done
Probably was a committee thing, but you get the point.
Reducing the risk of malware
Maybe ... wait ... what ARM malware?
Apple does it
Apple goes to great lengths to lock the OS on the iPhone and iPad, so why shouldn't Microsoft do the same? You really don't think Apple will revise its policies for the iPhone 5 and iPad 3 ...
Securing revenue from the back end
Some people like to take the hardware they've bought and paid for and get it to do things that it was never meant to do. These people don't do any harm, but as we've seen with the iOS platform, unlocking can become quite popular. While Microsoft still gets the money from a Windows 8 tablet being sold, it runs the risk of losing the chance of further revenue though app store sales and so on.
Platform lock in
The best way to get people to like Windows 8 is to force them to use it.
We won't know for sure why Microsoft has decided to do this, but it will be interesting to see what people make of the lock-in.