Toggling buttons on click
The selector for all edit_buttons can be expressed as a single selector $('div#personal_info button.edit_button'). 

I am tempted to rewrite the code to use closure scope to cache the selector values e.g. 

// Iterate using each to define cached values for selectors within a 
// closure scope 
$('.edit_button, .save_button, .cancel_button').each(function() {
  var button = $(this);
  // select all elements that need be toggled on click
  var toggled = $([
    button,
    button.siblings('button'),
    $('div#personal_info button.edit_button').
       not(button.parent().find('button.edit_button'))
  ]);
  // toggle each element separetely on click as the first element in a selector
  // defines the target visiblity of a no parameter .toggle()
  button.click(function() {
    toggled.each(
      function() {
        $(this).toggle();
      });
    });
});


The benefit of it is that less traversing is needed. Unfortunately the toggle method didn't work quite as I imagined it would when there are both hidden and shown elements in the selector when using jQuery 1.6.2. 

The above code is available through jsFiddle

From a maintenance/cleanliness point of view I'm a bit wary how this piece of code merges the concerns of 


Hiding all edit actions
Showing all edit actions
Displaying save and cancel actions for a specific edit action
Hiding save and cancel actions for a specific edit action


The result of all these goals leads to astonishment that is higher than the least possible. I don't really know what a good name for that function would be?

Also how and where are the event handlers for onclick events of .save_button and .cancel_button defined?