We all know that havew a plugin that automatic check for the latest version of wordpress and upgrade it.

The fact that WordPress Automatic Upgrade isn’t a default part of WordPress 2.5 is a crying shame! It installs just as you’d expect: you download the zip file, unzip it, upload the resulting folder into your plugins folder and activate it.
 

Once activated, you have a new entry on your Manage page in your blog’s WordPress admin, called Automatic Upgrade. When you activate it, it will walk you through the following eight steps:
 

1. Backs up the files and makes available a link to download it.
2. Backs up the database and makes available a link to download it.
3. Downloads the latest files from http://wordpress.org/latest.zip and unzips it.
4. Puts the site in maintenance mode.
5. De-activates all active plugins and remembers it.
6. Upgrades wordpress files.
7. Gives you a link that will open in a new window to upgrade installation.
8. Re-activates the plugins.

There is a fully automated mode, but we weren’t quite brave enough to try that. Considering that we didn’t experience so much as a hiccup on the two blogs that we upgraded to 2.5 using this plugin today (one was at version 2.2.1, and the other at 2.3.0), we’re more than happy to stick to the manual mode which involves occasionally clicking the next button and downloading a couple of backup files once they’re ready. Plus, it’s nice to know what’s going on in case there’s a failure and you have to recover manually, and the plugin is great about giving verbose explanations as to what is actually going on.

Author and Plugins Website: Here
Download: Here