>?WEEK(DATE(2007,12,29)) && returns 52 because is Saturday
>
>>?WEEK(DATE(2007,12,30)) && returns 1 because is Sunday
>
>It´s not a bug but a feature.

But what dictates that 30-Dec-2007 is week 1 and not week 53 in year 2007? If you look at 30-Dec-2005, it returns week 53 (so it is possible to have more than 52 weeks in a year). Why not consider the last two days as week 53 for year 2007?