A lengthly 17-pages document has been published on Microsoft's website (opens in new tab) (and others) detailing the major and minor changes that will come with Windows forthcoming Vista Service Pack.
This document describes many of the notable changes in Windows Vista SP1, with the exception of some updates to the Windows Genuine Advantage experience which we are still developing for our customers and will be released in a later build.
The most important hardware change is the added support for Direct3D 10.1 which will allow "3D application and game developers to make more complete and efficient use of the upcoming generations of graphics hardware" and is something AMD/ATI have been banking on.
The service pack will also try to iron out issues that caused many crashes and system hang, including Windows Calendar, Windows Media Player, and a number of drivers included with Windows Vista.
Uses will also experience an overall jump in performance with SP1 thanks to a number of minor adjustments including a boost to the effectiveness of Windows ReadyBoost.
Comments on a website that reported the Changelog showed that there were some glaring misses like the lack of support for vector-based icons.