Less Obvious New Stuff in WordPress 2.5

WordPress 2.5 has been officially released. The new look of the administrative interface, a Flash-based file uploader, and the plugin auto-installer are the new features that have been getting all of the attention. But here are some less glamorous changes that you still might want to know about.

• WordPress no longer allows you the option to compress your pages using gzip. Apparently gzip created problems for some people, and there are better server-side ways of doing this. However, I thought it was a simple way to reduce bandwidth and improve page load times, so for those interested, I created a plugin that restores the gzip feature.
• The persistent object cache has been removed. This means that no longer can you enable file-based object caching by putting define('ENABLE_CACHE', true); in your wp-config.php file.

  The object cache is still there, and you can take advantage of it with various plugins for PHP caching methods, such as APC, eAccelerator, XCache, and Memcached. As far as I know, no one has yet written a plugin to replace the file-based object caching that has been removed. Mahmoud Al-Qudsi mentions in the comments a new plugin to use file-based caching in WordPress 2.5.

• The meta “generator” tag that many themes have in their headers—you know, the one that says <meta name="generator" content="WordPress 2.3.3" />—is now added to the header via the “wp_head” filter. You need to know this for one of two reasons: if your theme (like most) prints the generator tag already, when you upgrade to 2.5 you’ll be printing it twice. More importantly, if you’re one of those people who hides the generator tag (for perceived security reasons), you’ll now have to remove the action call explicitly. remove_action('wp_head', 'wp_generator'); will do it for the header but not RSS feeds.
• Imports using WordPress WXR files will now import your attachments. This is a really handy feature, as before moving images from one blog to another usually required a FTP client and often messed up the attachment browsing in the new blog.
• New password hashing. Until WordPress 2.5, WordPress hashed passwords with a simple double md5 method. Because of security problems that could occur should someone obtain a copy of your database, password hashing was overhauled. If you’ve integrated WordPress users with another application and are counting on the double-md5 method, you may want to download this plugin that reverts to the system.