[tea-flow]

Google has confirmed on multiple occasions that this is the case. Different languages and geo-graphic regions require tweaks I am sure. US English != UK English.

See - http://googlewebmastercentral.blogspot.com/2011/04/high-qual...

For an example of Google announcing that the Panda update was now launching globally (as opposed to the US the prior month)

[franze]

also UK sometimes is a test market, why? (nearly) the same language as in the US, but not as a dominant market as the US. (the same reason why we german natives test new websites with switzerland)