I wonder if woodpeckers drinking from hummingbird feeders is a  
learned behavior.  In Arizona, Gila Woodpeckers are regular sippers  
at feeders.  I have never, either, seen that behavior here.  But is  
it so far from sapsuckers drinking sap?  It will be interesting to  
hear if others have seen this behavior here and if the phenomenon  
grows in frequency.