Just a quick update on this - we typically buy all our Macs from
shopandship. One of our 17" developed the issue in January and we followed the Apple return process (
http://www.apple.com/uk/support/macbookpro-videoissues/).
Laptop was returned via the retailer to Core 8th April and latest feedback from Core is that it will still take "several weeks" until it is repaired - not quite sure if this is due to Core relying on Apple or if it is a plain Core issue. It will be interesting to see if they actually repair or swop out with a refurb.
Has anyone here had better luck or are you guys also still waiting?