It's a new week, which means that it's time for a new Windows 10 Insider Preview build. Today's is 15051 for phones only, meaning that there's no PC build just yet. It wouldn't be surprising if there was one for PCs later this week though.
The new build follows 15047, which was offered to Fast ring Insiders five days ago. Just like with that one, 15051 doesn't contain any new front-facing features; indeed, Microsoft is working on fixes instead of features at this point.
The Windows 10 Creators Update is slated for April, which means that we should see an RTM build this month. During this period, you can expect to see Fast ring builds show up more frequently, and when one is signed off for RTM, it will be offered to the Release Preview ring, and then eventually to Production. Of course, there will likely be a couple cumulative updates in there as well.