Well I have to comment and share my experience about the above geo-targeting debate..
a UK site targeting UK customers and set in GWC as UK hunting long tails for a daily/seasonal long key-phrases.
Checking from my local IP (non US/UK) is giving me good SERPs for my key-phrases. Checking from a US IP giving me *almost* the same set of result. But checking from a UK IP (which is our target) is giving me totally different SERPs.
Even worse, checking .com and .co.uk is giving different set of results for each IP (non US/UK, US and UK ones)!
I don't see if that's something new due to the recent updates or this has always been the case, but with this insanity I am really considering purchasing a SERP monitoring service (not a software)!
Appreciate any useful input from UK webmasters.