Pull-to-refresh certainly is catching on (I expect my smartphone-addicted parents will discover it within the next 5 years), but I can also understand if there are some reservations about implementing it.

What should happen when the user is interacting with the Android device via a non-touch input device, such as a mouse with a scroll wheel? Scroll-wheel-up-to-refresh?

One of the worst edge cases is on sites with infinite scroll. Having to scroll up 47 pages in order to refresh is not great. It is also nice to refresh a page without losing one's place on it. For these reasons, I would like to see the refresh button remain, even if pull-to-refresh is implemented.