title: No generic implementation of OrderedDictionary?
body: <p>There doesn't appear to be a generic implementation of <code>OrderedDictionary</code> (which is in the <code>System.Collections.Specialized</code> namespace) in .NET 3.5. Is there one that I'm missing? </p>
  
  <p>I've found implementations out there to provide the functionality, but wondered if/why there isn't a generic implementation out-of-the-box and if anyone knows whether it's something in .NET 4.0?</p>