One of the earlier press releases[1] about this didn't mention anything about IoT Core. I think many people expected this would be something like the existing Windows RT.
The messaging about Windows 10 on the Pi 2 a few months ago was pretty bad and many people assumed it was the full Windows 10 desktop experience because so little info was released at the time. Only if you dug into the details released at WinHEC a month ago could you start to see that it's a shell for running simple Windows universal apps.
