Yes. I dare: Windows Mobile.
Just one of the instances where it seems Microsoft were ahead of the game (so much so, that it hurt them – surprisingly, not a unique experience on the Redmond front).
A single device that combines a phone, the internet, emails and messaging all into one?
Yeah, Windows Mobile did that.
Oh, but can you extend the functionality by installing these things called apps?
Yes. Also, counter point: remember how the first iPhone didn't do apps at all?
Oh well surely, this is just a case of dynamic convergence and Windows Mobile *must* have been developed roughly the same time as iOS? They couldn't possibly be more than a few months apart.