Possible Duplicate:
Comma before last item in a list

I grew up learning British English rules and we were taught that while using commas to list or enumerate items, there should never be a comma before the and. For instance:

I bought bread, milk, apples and oranges.

I've seen this rule less prominent these days, especially in the US. The same sentence would be:

I bought bread, milk, apples, and oranges.

While this usage would have my English teachers up in arms, it seems quite normal here. Is it more of a pseudo-archaic use, is it more enforced in British English?