Apple has updated their iTunes software to version 10.4. The new version has been designed with OS X Lion in mind. You can now switch iTunes to full-screen mode which is part of the features with come in the new version of OS X. You can get the latest version of iTunes using the Apple Software Update feature or by using this link.
Users who make use of plug-ins are advised that this update may cause certain plug-ins to stop working properly. You are advised to contact the developer of your plug-in regarding updates.