Loop through custom taxonomies and display posts

While I've been able to get this working for normal WP categories I've been unable to get it working for custom taxonomies.

I'd like to loop through each custom taxonomy (categories in my case) and produce a number of posts for each.

An example of the output would be:

Category 1post from category onepost from category oneread more category oneCategory 2post from category twopost from category tworead more category two

Of course it would repeat through any available taxonomy for the custom post type.