My understanding is that the revision of "50727" in the v2.0 of the CLR encodes the date of the release build: 2005-07-27. If this is true, what does the 30319 encode?
Note: my information comes from a blog of a member of the CLR team. Note 2nd comment on this blog post: http://blogs.msdn.com/b/abhinaba/archive/2005/10/28/486189.aspx.
Version 2.0 of the CLR was released on 2005-11-07. The revision number encodes nothing - it's just that, a revision number.
I see a range of timestamps on the .NET 4.0 files that span about 20 hours. The build ended early in the morning on March 19th, 2010 (UTC). So the 0319 part of the version is a very good match. The simple explanation is that year 0 for .NET 4.0 was 2007. Sounds about right for them starting to work on it.