* Also in additional hooks, hooks are now fired whenever modules are installed, uninstalled, enabled, or disabled. See
http://api.drupal.org/api/search/7/hook_modules for more info. This should pave the way for some nice DX patches in future unstable releases.
* In the DX clean-up realm, hook_user() and hook_nodeapi()'s $op parameters are now gone. Instead of having to switch on $op and figure out what in the world '$arg1' is in the 'load' context (UGH), you instead implement hook_nodeapi_load(&$node, $teaser, $page) and know exactly what you're dealing with.