Blackdown Java vs. Sun Java

Found an interesting "bug" (it isn't a real bug, but choose yourself): If you have a Date (no matter if java.sql.Date or java.util.Date) in Daylight-saving Time before 1981 Blackdown chooses the historical way (no Daylight saving Time between 1948 and 1980) and Sun does ignore this historical point.
This isn't a real problem until you mix up the two distributions (eg. client-server application)