Windows 10 build 16186 for PC is now under testing. The new Redstone 3 build 10.0.16186.1000 (rs_prerelease.170426-1507) was compiled on April 26, 2017. Windows Insider team is also testing Windows 10 Mobile build 15209 (10.0.15209.0 feature2).
Recently, Microsoft also released first Windows 10 Redstone 3 build 16184 and Mobile build 10.0.15208.0 feature 2 for Fast Ring Insiders.
Official Windows 10 Mobile Creators Update build 15063.251 is now available for download. However only selected Windows phones will receive the update. Read more details here.