Seems more likely Broadcom have been helpful than MS from what the RPi folk have said. I'd guess that they weren't originally expecting it to be feasible to get what appears to be a custom SoC made.
Note that when the B+ board was designed, they already knew the pinout of the new chip and were leaving space for it.
Note that when the B+ board was designed, they already knew the pinout of the new chip and were leaving space for it.