For Windows 10 Mobile users on the Slow ring that have anxiously been awaiting a taste of the Creators Update, today is your lucky day, as Microsoft is offering you build 14965. It's the first Redstone 2 Insider Preview to hit Mobile, although PCs got 14965 yesterday and 14931 last month.
Previously, Slow ring Windows phones were limited to receiving cumulative updates from the Anniversary Update, the last of which was 14393.448 just eight days ago. If you want to continue to receive these updates, you'll want to switch over to the Release Preview ring.
Since this is the first Windows 10 Mobile Creators Update Insider Preview in the Slow ring, you'll see all of the features that have been added in all of the Development Branch builds since the Anniversary Update was released. Sadly, there isn't much for phones just yet, but there are some minor new features, such as the ability to put your phone to sleep without breaking your Continuum experience.
Microsoft did announce new features that will be coming to the Creators Update though. Continuum is meant to be a more PC-like experience, which will finally allow for windowed apps and more.
If you're on the Slow ring, you can grab 14965 by going to Settings -> Update & security -> Phone update -> Check for updates. If you're not, go to the Windows Insider Program tab and tap Get started. When your phone reboots, go back and set it to the Slow ring.