This is an open question, or an idle wondering, depending how you view it.
I've noticed a particular variety of English which I'm calling 'Geek English'. I'm calling it that because I notice that it's particularly used by people who I would broadly identify as geeks, nerds, whatever you like, in a basically positive sense. You know, the kind of people who spend time playing online games, a lot of time in the internet in general, and are happy to be thought intelligent. It might also be people who would otherwise sound quite posh. For instance, some of the QI elves on their podcast 'No Such Thing as a Fish' have this accent (particularly Anna).
My question is, what characterises it and where does it come from? I haven't spent a lot of time thinking about it, but my immediate impression is that it has a vaguely transatlantic sound. There's a bit of what sounds like 'flapping' of the t's, and also the intonation is quite distinctive, and I think perhaps the vowels are a bit non-UK-like. But then, all this could be an incorrect assumption based simply on its unfamiliarity to me. A proper phonetician needs to study it.