Definitely H2,2011 or Q1,2012.
I have been reading up on any snippets of information to find out what the card is about...and thus would be cautious about looking for speed improvements with regard to Bitcoins or Namecoins.A GCN type architecture is suppose to be more Nvidia like [aka Fermi] and we know how well the Nividia architecture does w/ miners....there are also rumors I've been reading that it could be just a Cayman architecture with much more improvements which might not be a bad idea when...maybe OpenCL 1.2 compliance + 1 1/2-double the stream processors of current Caymans ?