Not Andrew but,
You wont get a straight answer from Sky! They have been very silent about the whole subject.
You could be in for quite a wait though,Amstrad boxes will last....
Rollout of the EPG was completed on Thomson And Pace boxes around august,then was halted for Samsung and Amstrad boxes as it was found to be unstable on those boxes and required 'ongoing development'.
It was then rolled out to around 30000 samsung boxes a fortnight ago( now believed to be a test batch) and there's been none since!
Sky will send you an "EPG upgrade" pack either in the post or by email a few day's before you get the upgrade.