It looks like Microsoft is preparing to release build 10074 of Windows 10 in conjunction with the start of the BUILD 2015 developer conference.



From SuperSite for Windows:

Today is a travel day for us as we arrive in San Francisco for Microsoft's BUILD 2015 conference which kicks off tomorrow with what is expected to be a keynote highlighting Windows 10 and other Microsoft technologies.

Since I am on the road that means the big desktop is back at home and I am unable to download and try out this build of Windows 10, 10074, which now appears to be the preview release for BUILD. Although, once it is released to the Windows Update servers then the HP Stream 7 that I brought with me will get updated to it.

  Windows 10 build 10074 is upcoming Insider Preview