Tested in the immediate window and is working for me (output as a comment)
Format(Now, "MM/dd/yyyy") '04/29/2009
Format(Date, "MM/dd/yyyy") '04/29/2009
Format(CStr(Now), "MM/dd/yyyy") '04/29/2009
Format(Date$, "MM/dd/yyyy") '04/29/2009
Format(CDate(Date), "MM/dd/yyyy")'04/29/2009
So whether it is string or datetime should not matter.
Edit: Saw your comment to Fredrik. It doesn't matter how it looks like when you save it to the db table (column date format would be a property of the db and not your program's (or vb's) responsibility). Just format the value as and when you retrieve it from the db.