Update: Adobe Dreamweaver CS4 shipped on October 15th, 2008 and is no longer hosted on Adobe Labs. You can find the latest information regarding this release on the new Dreamweaver CS4 product page on Adobe.com
Important information for beta or prerelease users
The Adobe CS4 Clean Script will help resolve installation problems experienced by users of Adobe Creative Suite 4 software. The script can clean up install records for any beta and prerelease installations of Adobe Creative Suite 4 or point products, such as Dreamweaver, Fireworks, and Soundbooth. The Adobe CS4 Clean Script is designed to not interfere with existing Creative Suite 3 products, but it allows you to specify if you wish to remove them as well.
The script can be downloaded from the Adobe Support Center.