This list details the changes made from WordPress 18.104.22.168 to 1.5.2. I tried to take the developer-speak out of the descriptions, but some items are inherently code-related. I produced this list by reading the changelog on WordPress' development system, and reading the changes in the code (not just the descriptions of the tickets that were fixed) for each change.
- WordPress now escapes special characters for insertion in the database for values submitted via XML-RPC (via programs like ecto).
- Posts submitted via XML-RPC should now appear in only the specified categories. (Hopefully fixes issues with categories submitted via ecto.)
- Posts submitted via XML-RPC now properly detect whether the URLs in the post have been previously pinged.
- Referenced to a defunct variable previously used to contain the default post category have been replaced with a proper check of stored options.
- Added code to prevent exploits on servers that have PHP's "register_globals" setting enabled.
- The word "Name:" on the Upgrade tab is now available for translation in international versions.
- Depricated references to old comment table variables have been removed.
- Pingbacks correctly return an error when the source of the ping does not include a link to the pinged page.
- When posts are posted by XML-RPC, the publish_post and edit-post plugin hooks are appropriately fired.
- The Pages editor now includes a "Save and Continue" button, just like the Posts page.
- Five new plugin hooks were added to allow customization of the comment moderation and notification emails. (comment_notification_text, comment_notification_subject, comment_notification_headers, comment_moderation_text, comment_moderation_subject)
- Trackbacks, Pings, and Enclosure detections now occur in a different place, so the delay while saving a post should be significantly reduced.
- When users are added via tha admin panel, the user_register hook is triggered, just like when users register themselves from the registration form.
- A plugin hook now fires when a category is deleted or added. (add_category, delete_category)
- The category list can now be made to exclude categories using a new plugin hook. (list_cats_exclusions)
- The comments feed for a whole site now includes the post titles with each comment for easy indexing.
If you're more interested in specific details of what was changed than this overview, please look at the Trac changelog, which is the scary hive of code and dev-speak that I have interpreted for you here.