I do it sometimes in Swedish, but never ever in written language. I used to do it way too much when "talking" to my rabbits a few years ago (early teens), and a little otherwise too, but not to a great extent.

I hardly ever write in Swedish outside Swedish class, so I very rarely communicate in written Swedish which means that I generally don't have a reason to use cutesy stuff there. I do it a fair bit in English, though, so if I were to start using MSN with Swedish friends more I'd probably also invent new spellings and stuff more.