Need review of example_element.module

Looks good to me, just need to build up the comments. If it's of any use to you, here is an attempt at a nice user-friendly description of hook_elements.

"Form elements are already familiar to anyone who uses Forms API. Examples of core form elements are 'textfield', 'checkbox' and 'fieldset'. Drupal utilizes hook_elements() to define these FAPI types, and this occurs in the core function system_elements().

By implementing hook_elements in your own module, you can create custom form elements with their own properties, validation and theming."

"Each form element has a #type value that determines how it's treated by the Form API and how it's ultimately rendered into HTML. hook_elements() allows modules to define new element types, and tell the Form API what default values they should automatically be populated with."

I like it... You could go into more detail in the header php doc about just what an element is.... a predefined form array with sane defaults and processing + a theme function. I think thats what I gathered from IRC talking with eaton.

$element['#value'] = array('areacode'=>'', 'number'=>'', 'extension'=>'');

There needs to be a space between the => and the other stuff.

'#description' => t("Another phone number, a fax perhaps?"),

should be single quotes in the t().

(sorry, those are nit-picky, only because this will be an "example" module. VERY nice example, btw!)

I'd also throw some more comments in there, to match the other example* modules. Explain a bit more about hook_elements (just like a two-liner or so).