Apple has released the golden master version of the Yosemite Developer Preview, in addition to the fourth Public Beta to its various testing communities. These being the golden master builds suggests they are going to be the final versions for public release, provided no major bugs are found.
Generally Apple has made the golden master build available to the public within a few days of its announcement, so Yosemite should be available very soon.
As with the most recent releases of OS X, Yosemite is going to be a free upgrade available from the Apple Store, so if you have a Mac that supports Yosemite and are considering upgrading, then be sure to prepare your Mac first. At a minimum, be sure you have a full backup of your Mac using Time Machine or a system cloning utility before running the Yosemite installer; however, you might look over a few additional preparation suggestions to ensure you can reinstall quickly if a problem occurs, and even take steps to test Yosemite before replacing your primary OS installation.
Even though waiting on upgrading might be a good idea for those not running Yosemite, If you are currently testing the public beta or developer builds, then be sure to install the golden master as soon as possible, as this will ensure any known bugs with the build you are running will be dealt with.