Microsoft has published the November 2015 Update for Windows 10, which brings it to the logical version number: 1511. It is not available to everyone though. The update is apparently being rolled out to users slowly, and manually pressing “Check for updates” will not fix it either. I've been doing that all day and still haven't got it. Those who want to receive it before Windows Update graces you with its existence will apparently need to either download the ISOs, or use the Windows 10 update tool. It was designed to bring Windows 7 and Windows 8.x to Windows 10, but it (apparently) can also be used on older versions of Windows 10 to update them to newer, public versions. It might remove the ability to go back in case of problems though, so be careful.
The update itself shouldn't be too surprising if you have been following our periodic check-up with the Windows Insider program. This is essentially the most recent build, although it apparently is installed without the big in-place upgrade process (although I have yet to do it myself, as stated above).
And, of course, WinBeta did a video walkthrough that highlighted the visible differences between July and November. I guess that's something to watch while you continually click “Check for Updates”. Or not.
Note that if you have only recently installed Windows 10, Microsoft will not push the new version to you just yet. They do not want the new build overwriting the image to bring you back to Windows 7 or 8.x, so they are waiting for it to expire.