We try to notify this list when API changes are made in Drupal 7, so contrib and custom developers have a chance to fix their code before they have the pain of figuring out why it's broken.

(issue) Theming the "Submitted by" text for nodes and comments:Previously in D7, the "Submitted by…" text for node and comment tpls was created with a t() function that resided directly in the node.tpl.php and comment.tpl.php. With this API change, the node's $name and $date variables are joined together inside template_preprocess_node() and printed as a $submitted variable in the node.tpl.php. The comment's $author and $created variables are now joined together inside template_preprocess_comment() and printed as a $submitted variable in the comment.tpl.php.

(issue) theme_menu_local_tasks() can now be changed with preprocess functions, allowing alteration of primary and secondary tabs.  Previously, theme_menu_local_tasks() took no $variables, so preprocess functions on it were impossible. Modules can now alter the primary and secondary tabs using preprocess or process functions.  Themes that overrode the old definition of theme_menu_local_tasks() will need to update their theme declaration to mirror the changes to the default implementation in includes/menu.inc.

(issue) Modules can now react to a change in an entity. The entity controllers resetCache() signature has been changed.

Thanks,
-Randy

--
Randy Fay
Drupal Module and Site Development
randy@randyfay.com
+1  970.462.7450