myCloud: Is self-hosting iCloud possible?
Somewhat. Not exactly.

You can run an Exchange server which will give you push email, calendar and contacts. This can be configured on all your devices (even pre-iOS 5). This is pretty much what you get from the equivalent iCloud stuff.

But there isn't a way to access the Documents in the Cloud or iTunes in the Cloud features without iCloud. (Although you could use Dropbox to store stuff, it doesn't work with iTunes or iWork). This is primarily because Apple wrote the services from the ground up, they aren't using an existing service. So while there are APIs, there aren't standards.

Apple might conceivably open a EU data centre in the future.