That is the page modification date. It has nothing to do with the case status updates.
Unless they change the structure or content of the page , this date will remain the same forever. The case status update is through their CAIPS software which interfaces with the CIC website. So your case updates are captured on CAIPS, not on the website. The Website is just a front-end for the client to see the case status.
If you see on all pages on the CIC website their is page modification date mentioned. Some are as new as 19-08-2010 & some are as old as even 11-2008.
E-cas updates are carried at Visa Office level & not CIO, Sydney. Usually Visa Office updates the e-cas on Monday/Tuesday local time.
That also affirms that the page modification date cannot be for e-cas as the page is universal for the entire world, whereas Visa Office updates are at Country level.