Microsoft has spent the last month or so working on "OS Core", making changes underneath the hood in the latest Insider builds that while they may not look much different, continue to stabilize and advance the platform.
Now, as Gabe Aul has been promising, it looks like we may soon be in for some bigger changes, if the latest build numbers and their significant jump are any indication. A website dedicated to tracking the latest internal build numbers (although not much more), Buildfeed.net, has just posted the version number of the latest build now testing internally at Microsoft, and that number has jumped from 11107 (from 3 days ago), to 14251.
While we don't have much more to go on at this point, we do know that Microsoft is planning a number of new features for "Redstone", including new Continuum features, extensions for Edge, and more. Current Windows 10 Insider builds are already "Redstone", although we're still waiting to see any significant and obvious changes. Hopefully this jump in build numbers signifies that some of those more obvious changes are on the way.
Thanks for the tip, Craig!