Apple IDE for developing widgets (unfortunately not for the iPhone as it seems):

• Tools – Dashcode Beta
  Dashcode is a new application for developing Dashboard widgets coming in Mac OS X 10.5 (Leopard). Dashcode is everything you need to create great Dashboard widgets.
  (tags: software macosx widgets dashcode)

Nice software to free your widgets from the dashboard:

• Mesa Dynamics
  Amnesty Widget Browser is a full featured widget manager for Mac OS X Tiger and Panther (10.3.9) that allows Dashboard widgets to have expanded capabilities as they run directly on your desktop via a convenient icon in your system menu bar.
  (tags: software macosx widgets amnesty)

Maybe a good starting point for having a look at ruby:

• Mr. Neighborly’s Humble Little Ruby Book
  (tags: book programming tutorial ruby)