I’ve been having an issue with the new blender 2.66
devs might be ignoring it as they think its an already fixed issue because there was a similar problem a while ago.
the file is here: http://www.crimsoneye.co.uk/UVGlitch2.blend
sorry file is too big to attach.
just click play and see if this is what you see:
if it is there is definately something wrong with the new build. atm blender-2.66-r54912.
Edit March 2013 : r54965