The Animated GIF linked in the URL, animates properly in Safari 3.2.1 release, but not in WebKit trunk.
I'm not sure which other GIFs are affected, this one is corrupted for sure, but it animated before, so it should animate in trunk, as well.
This will be fixed by the patch in bug 22108.
*** This bug has been marked as a duplicate of 22108 ***
Ooops, duped to the wrong bug.
Bug 23082 fixes this.
*** This bug has been marked as a duplicate of 23082 ***
this bug has been fixed. I recall either Adam or Benjamin were looking for a fix for this bug. Do you remember?
Shouldn't be an issue now, but thanks for pointing it out!