Systemwide upgrades are still listed prominently on the UK United website:

1K Upgrades

As a 1K® member, you are entitled to the highest upgrade privileges and priorities on United.®

Systemwide upgrades
Six confirmed upgrade certificates, valid on any United route worldwide, are enclosed in your 1K membership kit.

http://www.unitedairlines.co.uk/0419.htm

Mind you, the site does look a wee bit out of date. There is no mention of HK-49s, and upgrades prices are valid through 31 December 2000. We're still promised free upgrades on Shuttle flights, too.

:-)