Lovely shot Hank! I don't think this is a Cape May Warbler, the throat is too clean and no rufous on the face. My best guess is a first spring female Townsend's Warbler. According to Sibley's guide, first winter female Townsend's would have a yellow throat, with the streaking on the sides up to the throat area. I'm guessing that in a first spring female (almost 1 year old now), the bird would be very bright, but still have the yellow throat. Or, it could be a first spring male Townsend's without a black throat yet?
Dan - yes! I think you are absolutely correct. I didn't come across the Townsend's in hunting through my books, but I am much happier with that ID. My main problem with the Cape May ID was that the range was wrong (as I took this along the California coast - should have said that in my first post!) But Townsend's range matches much better. I continually have problems with female and juvenile color variants (though I'm probably not alone). :)