I don't remember turnarounds much under six months either, but what happened with RJ is that Tor cut down on the copy editing time, which lead to many copy editing mistakes (spelling errors, bad Ajah names and so on). In short, they rushed the book to the printer once they got it. For KOD, RJ insisted on getting back a full six months after he and Harriet were done with the book, so it could be copy edited properly. It wasn't the creative editing that was rushed, just the copy edit - the rumours that the story wasn't edited properly because RJ and Harriet had been rushed by Tor are crap. For TGS, Tor said they had accelerated the production process (layout, galley proofing, printing and so on), which they didn't use to do for the previous WOT books.

Things are bit different now, because for TGS the manuscript wasn't sent to Tor right after Harriet/Brandon were finished, but rather it's Maria herself who was hired by Tor to copy edit it (Rj's not there anymore to approve those edits... Maria would, and she's experienced as copy editor so they hired her to do it). In short, it means when Tor gets the manuscript from Maria there's no more work to do, it can go right into production. We can't compare this to the turnarounds in RJ's time, which included copy editing and approvals.

The turnaround after copy editing for TGS was somewhat over 4 months, and it's been described as tight by people at Tor.

With the same turnaround, if Maria and Brandon are done of August 17 it could mean they are aiming for a mid-december release or a January/February 2011 one. Or they'll put even more resources into production for a November release.