Although Microsoft will finalize the Windows 8.1 update in the next couple of weeks, the official update won't be released to the general public [or pushed to existing users] until October.
OEM partners will receive the update in August and are being given time to test and ensure drivers are updated to support the update.
I'm really disappointed that Microsoft is implementing an artificial delay to the much anticipated update.
Most analysts expect the 8.1 update to bring with it some new devices 7/8" tablets, new laptops, new all-in-one desktops [right before the holiday shopping season].