As those who have installed CS3 or any of the point products is now aware, the icons and interface experience isn’t the only things that have changed; the installer is brand-sparkling new as well.
When Adobe began assembling the pieces that would become Creative Suite 3, it looks very much like they desired a cross-platform, consistent experience. Having experience with the Blue Flavor studio previously, they were looking to leverage their experience in UI design.
The path to the solution they used is indeed quite universal: DHTML and XHTML, Javascript and CSS. Ajax serves as the communications conduit between the user, application, and system. Implementing the solution in this way provides a nimble installer that works equally well on both the Windows and Macintosh platforms.
Blue Flavor talks about their work with Adobe at the end of this link.