I just heard back from Jamie Cansdale, who used to maintain the Reflector.VisualStudio add-in. I had e-mailed him a while back wondering where the add-in was, because the write-up in Visual Studio Hacks made it sound like a sweet deal, but it was no longer available for download.
Turns out Jamie is also the maintainer for TestDriven.NET, and has released a substitute for the ReflectorVsAddin: it’s now part of TestDriven.NET. With the latest version, you can now right-click and Test in > Reflector. Kind of an odd menu selection to make, but it will pop Reflector open right to the symbol you right-clicked (there’s an animation showing it off on his “Reflector Add-In Lives Again” blog post). So, way better than having to open Reflector, browse to the right assembly, navigate to the right namespace, etc.
I asked him if the original add-in was still available, since having Reflector right there inside Visual Studio would have been really cool. His response: no, it’s not available, because there are Reflector add-ins that don’t play nicely if they happen to get loaded inside Visual Studio. So I guess the world is stuck with popping up a separate instance of Reflector. But I think I can live with that.