Apple promised to release Leopard in October, but hasn't set a specific date that they're willing to share with the world. It seems likely that it'll be towards the end of October due to the sheer volume of bugs reported in recent builds of their newest OS, and the fact that nobody has been talking about the discs going gold just yet.
A new pre-release version of the OS seems to have squashed a lot of bugs, and might fairly be termed a beta:
“People familiar with the new release say it contains only two known issues and may be considered the first of several release candidates, the latter of which would eventually be declared Gold Master and shipped off for duplication and retail packaging.
Of the two known issues in build 9A559, one relating to archive installs appears to be the most critical. Those people familiar with the matter say archive installs from Tiger to Leopard may fail on some Power PC systems if the user attempts to preserve their user settings. To remedy this problem, Apple reportedly suggests that users perform an upgrade install, a clean install or opt out of preserving user settings.
The second known issue affects users who have HP printers connected to their system or are upgrading from a Tiger system with an HP printer that had previously been configured. Though Apple did not specify the root of the problem, it recommended that these users perform a custom install of Leopard and de-select the HP printer drivers in the installer. The proper drivers would be delivered via Software Update following the Leopard install, the company added.”
Since most new commercial operating systems experience some teething issues post launch, we're left wondering if Microsoft will make a few advertisements to pay Apple back for some of their unkind abuse of Vista during its launch earlier this year.