Much of this discussion http://groups.drupal.org/node/62588 came out of Jen Simmons' talk: http://extras.jensimmons.com/drupalconsf2010/buttons_in_drupal.pdf

Her call was for a Drupal Module Developer UX Guide.

Her bullets included:
The assumption is these are UI guidelines for administrative interfaces, rather than general site or theme implementation guidelines.

Examples of UX style guidelines:
Examples of pattern libraries:
Existing references:
TO DO:
This should result in a pattern library of the existing practices within Drupal 7 Core administration interfaces.

These are not necessarily the best patterns, but implementing along these guidelines would result in a consistent experience.  It would be reasonable to note this document as a guideline and discuss enforcement, coder module support, etc. at this point.

After this is done, then we can talk about whether they are the best patterns to be using, and explore alternatives.