If you used UTW for your tagging system, WordPress 2.3 has a function to translate all your tags into the new native system. People say simple is better and this simple new feature makes UTW obsolete. On my blog you can see the “related posts” section after each post. This is also a helpful plugin by Denis Pao Pao that works with the new tagging system. If you re waiting to upgrade this might be the reason to go for it.