Bantam Spectra have released the finalised cover art for their new paperback and tradeback editions of A Song of Ice and Fire. As mentioned previously, this is the Larry Rostant art used on the current UK editions of the books, with some changes (A Game of Thrones has the cover from the UK A Dance with Dragons). The final covers differ from the drafts I've posted previously only in emphasising the HBO tie-in banner a bit more and changing the background colours on the first two books.
The new editions should hit American bookstores on 22 March, along with a special HBO tie-in edition of A Game of Thrones in tradeback and paperback (we're still waiting for the final version of that).
In the UK, Voyager have no plans to revise their artwork, I am informed, though the HBO tie-in edition will also be released (in a new typeset) here, possibly not until a week after the US.
EDIT: I've been told the new editions have already hit some bookstores in the USA and Canada already.
EDIT2: Winter is Coming has discovered the apparent final version of the HBO tie-in cover.
EDIT3: Sub Press are reprinting the first two limited editions of A Song of Ice and Fire (previously handled by Meisha Merlin before they imploded) and also have 30 completed pieces of art for A Dance with Dragons. There's just a couple more which will need to be inserted once they have the final manuscript, then they can move into production. So the limited ADWD should be available soon-ish after the regular edition.