You can get the NuGet package here: https://www.nuget.org/packages/MetaWeblogSharp/
The source code is available on CodePlex: http://metaweblogsharp.codeplex.com
While testing it out against my a Squarespace-based blog, I discovered that I needed to disable the use of the 100 Continue header for reliable communications.
This blog MSDN blog post provides a great summary about the issue: http://blogs.msdn.com/b/fiddler/archive/2011/11/05/http-expect-continue-delays-transmitting-post-bodies-by-up-to-350-milliseconds.aspx
In the end the fix was simple:
var request = System.Net.WebRequest.Create( “http://somefakeurl.com” );
var wr = (System.Net.HttpWebRequest) request;
wr.ServicePoint.Expect100Continue = false;