This may seem a bit farsighted for some, but I'm currently happily enjoying SPG Plat and don't intend to switch to Hyatt immediately.
These are specified in the T&C:
Qualify for Diamond under this promotion in 2009 = Diamond through Feb 2011
Qualify for Diamond under this promotion in 2010 = Diamond through Feb 2012
Following that logic...
Qualify for Diamond under this promotion in 2011 = Diamond through Feb 2013???
Registration for the promotion is open through December 2010, so if you register in December 2010, your 180 days goes through May 2011. If you complete the 15 nights in May 2011, do you still only get status for 2011, do you get it through 2012 (Feb 2013)?
This is probably a question for somebody from Hyatt. Karen?