I recently installed numpy and scipy in a new virtualenv on my OS X 10.10 machine and was very pleasantly surprised to see them being installed directly from wh

I recently installed numpy and scipy in a new virtualenv on my OS X 10.10 machine and was very pleasantly surprised to see them being installed directly from wheels instead of being rebuilt (installation time was a nice 1min compared to 10+ min before). Does anybody know if the wheel format is now supported/standard on PyPi or was this caching of my local pip?