First of all, as guys at IEBLOG reported, IE8 MUI packs for Windows XP (and also Windows Server 2003) are now available and have the following languages: Arabic, Chinese (Traditional), Chinese (Hong Kong), Czech, Danish, Dutch, Finnish, French, German, Greek, Hebrew, Hungarian, Italian, Japanese, Korean, Norwegian, Polish, Portuguese (Portugal), Portuguese (Brazil), Russian, Spanish, Swedish, Turkish, Bulgarian, Croatian, Estonian, Latvian, Lithuanian, Romanian, Slovenian, Slovakian, Thai. This is great for those who use localised versions.
Another interesting thing is that IE8 renders sites from Intranet security zone in compatibility view by default, unless the page specifically indicates that it should be rendered in standards-compliant mode (either by corresponding META or HTTP header).
However, this behaviour can be controlled from Group Policy. This is one of the most valuable benefits of using Microsoft technologies – you get great level of integration out-of-the-box.