Resource database update time

Hi everybody,

I just queried Resource database update time on my SQL Server 2008 by using

SELECT SERVERPROPERTY('ResourceLastUpdateDateTime');
GO
and the result is
2012-06-28 10:36:40.883

I am a little confused as I use the system everyday. I created database, table, etc.... Can anybody help me to understand the meaning of ResourceLastUpdateDateTime? 

Thank you!