The status period has absolutely nothing to do with the date you qualify. It has everything to do with the preset qualifying periods. Being your current status is good till December 2012, any new status you obtain within the current qualifying period will also be good till only December 2012. In your case, it sounds like you signed up for Asiana Club in November 2008. If so, your qualifying period runs till November 2010. Any status earned before November 2010 will expire in December 2012 (November 2012 + 1 month grace period). In November 2010, on the aniversary date of your joining Asiana Club, your qualifying miles will be reset to 0, and you can then start earning miles towards status that will be good till November 2014.

All of that of course applies to status up to and including Diamond +. Platinum is good for life so no periods there.

The above applies only to the new rules. I have no desire to learn the old rules, being I wasn't a member then.

Hope that clears up the confusion.