Normally, it takes three votes to delete. It still does, though the mouseover tip for a question with one delete vote cast on it already appears to be stuck at '1'
And then after casting a delete vote on it:
And if I've cast the first delete vote:
The above examples are from P.SE, and while I don't have the privs to verify this being the situation on other sites, this has been confirmed on at least SO and is likely network wide.
Child meta dups: