[kia]

I think strategically it's a wise move. For MS 7.5m is a small sum. In case IPv6 will not be deployed at the speed we all want their investment will pay off tenfold because IPv4 addresses will be gold. They try to hedge the address exhaustion risk.

[rbanffy]

They probably can measure the adoption of IPv6 from the usage data Windows desktops volunteer back to MS. That said, I would guess they predicted (at least in March) a scarcity of addresses for their cloud offering before IPv6 becomes widespread.