Windows 8 has been finalized and the RTM version is heading to manufacturers. This welcome news was dropped by Microsoft themselves on their blog. Here's a quote with a few more details,

Today, I am excited to announce that Windows 8 has been released to manufacturing (RTM)! This means we’ve completed the product development and testing of the product and have started handing off the final code to our OEM partners. They can now begin preparing new Windows 8 PCs and devices they’ll introduce starting with General Availability. For more on RTM, I suggest reading this blog post from Steven Sinofsky on the Building Windows 8 blog.
It's great to see Microsoft finally knocking things out with Windows 8. This OS will be the most significant change that MS has ever made to Windows. Moving from a KB & Mouse driven ideology to a touch-screen is a huge step. Luckily, Windows 8 has a dual-mode feature so you can actually go back to doing things the traditional way if you need to.

Source: Windows 8 has reached the RTM milestone