Plugin forms for signup module

I've been working on expanding the 'Name and phone number' form that signup module currently comes with.

The idea is that the form takes pane plugins -- the same sort of idea as Ubercart checkout panes. Modules provide plugin panes, and each signup-enabled node has settings to enable them and place them in order.

So far I've reimplemented the built-in form, and added support for core Profile module and webform.

Code: http://github.com/joachim-n/signup
Issue: http://drupal.org/node/29568#comment-2454196

Pictures:

Node view showing a signup form built from several panes:

Node settings: