OS X Mavericks is dangerously close to release and is expected to go Gold Master (GM) within the next few days to a week. That's the word from 9to5Mac.
9to5Mac claims that Mavericks' GM is past due, but that Apple has been whittling away at it to fix critical bugs prior to release. OS X Mavericks' specific release date hasn't been revealed by Apple, but it's been widely speculated that Apple will release Mavericks some time between the middle and end of October. Apple is expected to make its fiscal year 2013 fourth quarter earnings report in the same time frame, and often has an October event to introduce new Mac products.
OS X Mavericks was unveiled in June at Apple's Worldwide Developer Conference in San Francisco. It has a number of improvements like tabbed Finder windows, a new Maps app and a new iBooks app, along with under the hood improvements to efficiency, performance and battery use.