Nov 3, 2009, 10:17 PM
From the iPhone Developer FAQ (http://forums.macrumors.com/showthread.php?t=518968) at the top of this very forum:
The difference between a registered and an enrolled developer:
Registered: register at Apple, agree to the SDK license, and use the SDK with the included iPhone simulator only.
Enrolled: Pay $99 and be allowed to provision actual iPhone and iPod Touch devices to test your software.