Yes I have noticed lots of strange happenings lately with AdWords as first mentioned in my post here: [webmasterworld.com ].
Iíve noticed it previously on the last few weekends but as of today the UK AdWords SERPs are all over the place. Constantly being shaken up. It seems that all previous ranking factors are out the window.
G is up to something and it *appears* that they're rotating ads so that the "sleepy" campaigns and accounts are squeezed for some of their unused budget.