Updated installer : The installer now only performs networkless installations using the packages and ebuild tree on the LiveCD. It also contains numerous fixes for extended and logical partitions.
Improved hardware support : Moving to the 2.6.24 kernel added many new drivers for hardware released since the 2007.0 release.
Complete rework of profiles : Restructuring profiles allowed significant cleanup of redundancies, reducing developer maintenance and confusion. The difference for you is that profiles now appear in /usr/portage/profiles/ under default/linux/ instead of default-linux/. See the upgrading guide for more details.
Xfce instead of GNOME on the LiveCD : To save space, the LiveCDs switched to the smaller Xfce environment. This means that a binary installation using the LiveCD will install Xfce, but you're still free to build GNOME or KDE from source.
No LiveDVDs on x86 or amd64 : In the interest of getting the release out, the release engineering team decided to postpone LiveDVDs because of problems in their generation. They may show up later—if so, we'll let you know.
Updated packages : Highlights of the 2008.0 release include Portage 2.1.4.4, a 2.6.24 kernel, Xfce 4.4.2, gcc 4.1.2 and glibc 2.6.1.