No longer waiting to hear back about the NDSEG fellowship...(note the title changed) There's a good chance that you are reading this because you googled something like "NDSEG blog," so don't think that you haven't heard back because you simply didn't win. As of April 15th, I don't know anyone who heard back from NDSEG. Good luck all! We will find out soon enough.
As of April 28th, everybody that I know who has applied already heard back.
Update: some people heard back (positive replies!) last Friday (the Friday following April 15th)
Update++: I didn't win the NDSEG fellowship; however, I'm still quite happy with winning the NSF fellowship.