"We manage award availability on our Star Alliance partners just as we do with United's own saver awards," said Jeff Kovick, a United spokesman ... "It is an ongoing balance of ensuring we meet our customers' interest in award travel on partner carriers with United's need to generate revenue on our own flights."
So there you have it... from the horse's mouth.

Full story here:
http://washingtontimes.com/news/2008...award-tickets/