I need to reask my old question, I probably shouldnt have asked it at 1am :P
It seems that some attributes are not being found using jquery\'s attribute selector:
There is no "list" of unsupported attributes because there shouldn't be; this is a bug in jQuery.
Here are the open tickets on this:
Apparently the common denominator between the bugs is that jQuery is comparing the selector string you specify against the full URL as opposed to the actual action/src attribute as it is defined in the HTML. This explains why the attributeEndsWith or the attributeContains selectors do work in this case.
I would recommend just giving the form/image a class/ID and getting it over with.