Apple announced OS X 10.9 Mavericks earlier this year at the Worldwide Developers Conference 2013.
A Golden Master (GM) version of the new operating system was released to developers and certain other users last week. GM indicates that the code is ready for release.
Although no release date has been announced for OS X 10.9 Mavericks, most speculation seems to centre around the week of 21 October.
10.9 marks a change from the 'big cat' naming convention used internally or publicly for (Mac) OS X since version 10.0 Cheetah. From 10.9, Californian place names are being used - Mavericks is a surf spot on the San Francisco peninsula, to the north-west of Apple's Cupertino headquarters.
Meanwhile - and unsurprisingly - work is already underway on OS X 10.10.
Where the 'big cat' names were initially intended as internal codenames and were later adopted for public use by the company, Apple is now finding internal inspiration from wines - 10.9 was codenamed Cabernet, and 10.10 is apparently Syrah if reports of sightings in web server logs are to be believed.
According to various reports, OS X 10.10's user interface will continue to move in the direction of Apple's mobile devices, with a look that will pick up elements from iOS 7 and the recently-facelifted iCloud.
But Apple does have a habit of introducing new technologies when it updates the Mac OS. Examples include App Nap in 10.9 (to reduce the demands made on the system by hidden applications that are not doing useful work) and Power Nap in 10.8 (so Mail and certain other applications can stay up to date while the system is sleeping).
We have heard no rumours about what may be under the hood in 10.10.