How do you work with a programmer with a radically different coding style?

That's a human communication issue. Just talk to each other. Not through code, in person.

Communicate with the other developer. Agree on a coding style that combines best of both worlds ?

It depends.

If the other developer isn't particularly easy going, then I tend to just go with their programming style even if I disagree with it rather than force the issue - in this case its really a matter of whats more uncomfortable, their coding style or the grief I'll get by making a fuss?

If the other developer is more open minded then I might discuss things like coding / naming standards (I would hope that things like the overall architecture would be discussed anyway)