FORTUNE — The full keynote in which Microsoft (MSFT) gave its developers “the details they need to know” lasts nearly two hours. But the executive briefing is Joe Belfiore’s 60 minute presentation that starts at the 6 minute mark.

Most press reports highlight the key hardware features — support for multi-core processors, MicroSD chips, near field communications, higher resolution screens, etc.

But Belfiore leads with the news that might give Apple (AAPL) and Google (GOOG) pause: Microsoft has abandoned the Windows CE kernel. From now on its smartphones will share a “common core” with Windows 8. That means its three platforms — PC, phone and tablet — will have common networking, security, media and web browser technology, device drivers and file systems.

This is Microsoft playing to its strength: the 1.3 billion people around the world wedded for one reason or another to the Windows desktop operating system.

It’s a smart move. It’s too early to tell if it’s coming too late.