A random collection of noteworthy links:
Spartan PM Jacob Rossi wrote about the new Project Spartan rendering engine.
Windows 10 build 9926 has been released; Spartan is not yet in it, but you can enable the new EdgeHTML engine using the about:flags page; set the Experimental Flag to Enabled. Included in the build are support for HSTS, HTTP Live Streaming, Video Tracks, DOM L3 XPath, and improved developer tools make an appearance.
EdgeHTML includes support for Content Security Policy, a powerful technology to defang XSS and content-injection attacks. David Risney recently released a Content Security Policy rule generator extension for Fiddler. Surf your site with Fiddler running and this extension will compute the appropriate CSP rules for your site.