The latest word is that Microsoft could announce the Release To Manufacturing (RTM) of Windows 8 this month, the last step before the product is generally available.
So far Microsoft has only said that Windows 8 will be available by the end of this year. But it's now July and Microsoft should have a better idea of when the next generation of the PC operating system will be available. Partners, after all, need to develop their plans for selling the product and upgrading their customers.
Most speculation on Windows 8 availability has centered on October. But speculation isn't much for partners to build business plans around. Probably the biggest applause line Ballmer can deliver in his Monday keynote speech is a specific ship date for Windows 8.