Paul and others,
 
When Dave Powell and I observed the bird 2 weeks ago it was very active, but not tail-pumping.  I was a little surprised thinking it was likely a western vagrant.  I have observed tail-pumping twice before on Nashville Warblers in MD, once this past Thanksgiving weekend with Mike Burchett and Jim Stasz in Harford County and once in mid-October at Terrapin Park in Queen Anne's County.  I am not quite convinced that those birds were ridgwayi as I don't have good photos to study the birds in detail. 
 
As for Richard's comments of "does it really matter?" There answer is most definitely "YES!"  It may not count on any "official" list, but it does matter when it comes to the distribution of birds in MD.  Also, if people start seriously looking at identifiable forms and subspecies, they will not be caught off guard when the "split" does occur.  This happened with the Cackling Goose split in 2004.  Marylanders already had an idea of the distribution and regularity because a few birders had been documenting "small race Canadas" for several years.  
 
Another "not yet split" example is Palm Warbler.  The "Yellow" and "Western" forms seem to have entirely different migration patterns in the state, but more records are needed.  Even if you can't "officially" add it to your list, you can still add it to your personal records and makes this birding game a little more interesting (for me at least).  
 
I could write quite a bit on this subject, but class is starting in less than 2 minutes.
 
Good birding,
 
Matt Hafner
Bel Air, MD