WordPress 3 has definitely made some well-deserved changes. Among these; the custom menu option, the mass update function, and the merging of WordPress and MU. In addition to the hundreds of bug fixes and security updates. It has become more than blogging software and is now capable of competing with CMS software on a large scale. There is no limit to WordPress’ functionality.
Custom post types now allow even further categorization of your blog or website. They’ve also updated the default theme which now allows for a more unique blog using only the default (Twenty Ten). Also, you should note that all of Viper Amped’s WordPress themes work with WP3 but not all the features (like custom menus) may be available.
*Will Update If New Information Comes Up*