And if it helps anyone, here's a great post on bumblefoot (and surgery too): http://www.the-chicken-chick.com/2011/07/bumblefoot-causes-treatment-warning.html
Hope that helps!
That one is kind of large. I think you are going to have to remove it. It is very similar in size to the one I posted pictures of on page 1. I think after a few soakings and a couple of poultices it should lift off easy enough without a bunch of cutting and digging.