It's becoming a much less surprising thing. While younger men and older women have been enjoying each others company probably ever since the dawn of sexual beginning it sometimes takes a fair bit of publicity for an idea like that to become famliar and "main stream".
A fairly recent and well known celebrity couple are actress Jennifer Aniston and singer/musician John Mayer. Aniston was born in 1969. Mayer was born in 1977. That gives them a modest 8 year difference.
Halle Barry was born
Date a Cougar