Parallel.ForEach missing from Reactive Extensions for .Net 3.5

This article mentions that the Reactive Extensions for 3.5 contains a backported version of System.Threading.dll but when downloading the latest version from the Rx Site this assembly is nowhere to be seen and the Parallel class seems to be not present in any of the included assemblies either. Anyone happen to know what happened to this assembly?

U开发者_StackOverflowPDATE: I've found a working download link for an older Rx Release that still contains the backported System.Threading assembly here.

http://blogs.msdn.com/b/rxteam/archive/2012/08/15/reactive-extensions-v2-0-has-arrived.aspx

The latest version takes a dependency on .NET 4.0 or 4.5 , so there is no need for a back ported TPL runtime.