Some of you may have noticed the shiny new color picker in WordPress 3.5. This was a great example of collaboration between a commercial service and open source: we developed a color picker for WordPress.com to scratch our own itch, then offered it to WordPress.org. They then pushed us to make it so much better than it would have been otherwise. Everybody wins.
Find out more, including how to use it in your next WP project, on make/core: New Color Picker in WP 3.5.