XPathReader is/ was an implementation of a forward reading XML parser (built on XMLReader) which allowed you to register XPath queries for it to find (or at least a subset o
I suspect that LINQ-to-XML happened. However, the Mvp.Xml project on CodePlex has many features that relate to this. You might want to take a look at the XPointer.NET library they have developed and the XPointerReader.
Also, you might want to take a look at this FastXPathReader on CodeProject (I don't know how effective it is).
As for XPathReader, all I could find were the links you provided and links associated with those. It looks like it disappeared. Like I said, I think LINQ-to-XML was the outcome, but I'm just guessing.
Found myself asking the very same question today as I was meaning to build a BizTalk pipeline component to parse incoming message for specific elements.
After some googling, I found out that the XPathReader assembly is shipped with BizTalk and is residing in the GAC.
Just reference the GAC assembly Microsoft.BizTalk.XPathReader.dll and you're up and running!
It seems that ms released this over here and the install includes source code.
XNode.ReadFrom combines the power (and supported status) of Linq to XML with the ability to process a stream rather than loading the entire file into memory
http://msdn.microsoft.com/en-us/library/system.xml.linq.xnode.readfrom.aspx