there are several different ways for modules to restrict access to users. There're various hooks and design philosiphies. These methods should be discussed in a page that outlines how you would implement each of them.
Discuss db_rewrite_SQL, hook_perm, hook_access_grants, etc.
Comments
Comment #1
Barry Madore commentedchanging component
Comment #2
dkeays commentedI'll take this one.
Comment #3
arianek commentedthis appears to have been abandoned - there is an existing page here: http://drupal.org/node/270000 that needs some updating (the comments give a good indication of the needs).
Comment #4
arianek commentedoh look, some nice people have been updating this page. :) marking fixed