WordPress 1.2 was significant because it represented a fully mature product with features above and beyond other tools in the market. It was released right after Movable Type had some issues with their licensing and many users were looking for a new system to move to. Version 1.2 was used by an order of magnitude more people than any other release.
Released 2004-10-6. Release post.
wp-admin/admin-header.php
wp-admin/bookmarklet.php
wp-admin/categories.php
wp-admin/edit.php
wp-admin/options.php
wp-admin/post.php
wp-admin/wp-admin.css
wp-comments-post.php
wp-includes/functions-formatting.php
wp-includes/version.php
wp-login.php
Released 2004-12-15 to address security issues and a few bugs. Release post. Note if you're running PHP5 you may need to apply this fix.
wp-admin/admin-functions.php
wp-admin/admin-header.php
wp-admin/auth.php
wp-admin/bookmarklet.php
wp-admin/categories.php
wp-admin/edit-comments.php
wp-admin/edit-form-advanced.php
wp-admin/edit-form.php
wp-admin/edit.php
wp-admin/link-add.php
wp-admin/link-categories.php
wp-admin/link-manager.php
wp-admin/options.php
wp-admin/post.php
wp-admin/templates.php
wp-admin/upgrade-functions.php
wp-admin/upload.php
wp-admin/users.php
wp-blog-header.php
wp-comments-post.php
wp-includes/functions-formatting.php
wp-includes/functions.php
wp-includes/version.php
wp-login.php
wp-settings.php
xmlrpc.php