I'm excited to see that there is discussion going on here! I might suggest that the "manifesto" author did not say "I'm a PHP developer" to be limiting (i.e. I only write PHP) but to contrast with being e.g. a "Cake developer" or a "Rails developer." Assuming this is a reasonable interpretation, he is actually making the same "Don't tie yourself to one framework" point that OP is making here. So: agreement! (I think.)

I don't know how relevant this is but I couldn't help but notice that the "hammer" analogy for frameworks was an interesting choice in light of Joel S.'s well known "Hammer Factory Factory" article. http://discuss.joelonsoftware.com/default.asp?joel.3.219431.... Was this a coincidence or intentional? Anyway I thought it was a funny coincidence. :)