(DT_STR,4,1252)YEAR(GETDATE()) + RIGHT("0" + (DT_STR,2,1252)MONTH(GETDATE()),2) + RIGHT("0" + (DT_STR,2,1252)DAY(GETDATE()),2)
Update: Thanks to Anonymous below who pointed out that the code-page ought to be 1252 (rather than 1253) since this is usually the default for most SQL installs (not that 1253 will break it). As you can see I've updated it. Also if you want a Unicode version you can do this:
(DT_WSTR,4)YEAR(GETDATE()) + RIGHT("0" + (DT_WSTR,2)MONTH(GETDATE()),2) + RIGHT("0" + (DT_WSTR,2)DAY(GETDATE()),2)