C# & .NET for Smartphone Apps?

Question

Hi guys,

I'm interested in the possibility of writing aps for Smartphones. I don't have a Smartphone as yet & I was wondering if anyone might be able to tell me if certain Smartphone operating systems allow their apps to be written in C# .NET?

I'm guessing that the 'Windows Phone' operating systems would but are Microsoft as accepting of independently written aps the way Apple's App Store is?

Do Android, Palm WebOS & Apple allow C# .NET programming?

As I don't have a Smartphone as yet, I hoped to buy one with an operating system that allowed C# programs to be written for it, so that I could start writing aps for them. Could anyone offer advice?

Thanks very much indeed,

Dan : )