Dunno if anyone saw this, but..
Expired 500-mile Upgrade: Conversion Registration

"In response to customers’ feedback on the change to the 500-Mile Upgrade Program effective June 1, 2007, we are offering our current Global Services, 1K, Premier Executive and international customers a one-time only registration process. This will allow you to continue the conversion of unused 500-mile e-upgrades to miles upon scheduled expiration."

http://www.united.com/page/article/0...nk=%2F500miles