The main 'Threshold' branch of Windows 10 just got itself a big 'Patch Tuesday' update, for desktop/laptop/hybrid/phones, with the changelog quoted below. There's definitely some stuff below that's mobile-relevant. Build 10586.218 is now available as an update to all phones upgraded to Windows 10 Mobile, even if they're not officially approved, i.e. this is for both production W10 phones and all Insider-registered devices. Happy downloading!

* and on the 'Release Preview' ring within Insiders, since the Fast and Slow rings are now for Redstone only.

Here's the official changelog, applying to desktop and mobile, so not all items are directly relevant, but still...

This update includes quality improvements and security fixes. No new operating system features are being introduced in this update. Key changes include:

• Improved reliability for Internet Explorer 11, .NET Framework, wireless LAN, Microsoft Edge, Windows Update, logon, Bluetooth, network connectivity, map apps, video playback, Cortana, USB, Windows Explorer, and Narrator.
• Fixed issue with connectivity of USB devices until OS restart.
• Improved discoverability of printers when a device resumes from sleep.
• Fixed issues with lock screen.
• Support for visual voicemail on dual SIM phones.
• Fixed issue with audio playback using Groove music and other music apps on a phone.
• Fixed issue with revised daylight savings time.
• Fixed additional issues with shutdown delays, Narrator, Cortana, roaming data usage, buying apps in the Store, video playback, facial recognition, Bluetooth pairing, Microsoft Edge, logon, Internet Explorer 11, Live Tile updates, .NET Framework, and Microsoft Installer (MSI).
• Improved security for CSRSS to address security feature bypass.
• Fixed additional security issues with Security Account Manager Remote Protocol, HTTP.sys, secondary logon, Microsoft Graphics component, .NET Framework, CSRSS, Microsoft Edge, and Internet Explorer 11.

For more info about the security fixes in this update and a complete list of affected files, see KB3147458.

You've got to love the huge number of apps and featured mentioned under 'Fixed additional issues with'... Build 10586.218 does seem like a significant update under the hood - and it also marks the point in time where we can expect 'Patch Tuesday' updates to our smartphones in the same way that we've become used to with our laptops etc.

Aha, we now also have a more specific changelog for Windows 10 Mobile, going into a little more relevant detail:

• Reliability, performance and stability improvements.
• Support for Visual Voicemail on Dual SIM phones. 
• Improvements for Bluetooth connectivity, including the reliability of connecting to and staying connected with Bluetooth devices. 
• Fix for a problem that caused audio playback to get occasionally interrupted in Groove Music and other music apps when phone display was turned off. 
• Improvements for Microsoft Edge browser, including support for configuring a prompt before a file download occurs, support for background downloads, and a fix for a problem where opening a link from an another app wouldn’t load the web page. 
• Reliability improvements for Cortana reading text messages aloud and usability improvements for Quiet Hours feature. 
• Improvements for Store reliability, including a fix for a problem that prevented some apps from being updated and installed. 
• Fix for a problem that occasionally caused some apps to show blank tiles after upgrading from Windows Phone 8.1. 
  Improvements for PC connectivity via USB on some phones that were upgraded from Windows Phone 8.1.

This update doesn't apply to any Insiders already on Redstone, of course, up in the build 14xxx.xxx region. For these brave souls, a further update is expected later this week.