The Windows 10 Insider Preview Build 10565 went out last week for PC users, and now Build 10549 has arrived for mobile users apart of the Insider program.
Be warned, Microsoft discovered a black screen bug with this build, so if you want to install it without issue, you must go back to Windows 8.1 using the Windows Device Recovery Tool, install the Insider app, choose the Fast ring, reboot, then download the build. There are a few other issues with missing apps, notifications, WhatsApp calls, and more, too. Though they all have workarounds, there is some level of hassle involved. If you can't be bothered with any of this, take this news purely as a look at what's to come.
The main focus of the update is improving texting. You get a new text box in the Messaging app that can expand as you enter text, Unicode's more global set of "diversity" emojis, and a fix for the touch keyboard disappearing after texting.
Apart from that, expect Cortana support if you live in Australia or Canada and a variety of bug fixes. Hit the source if you want the lowdown on all those.