[rcxdude]

There's an example of a true-colour GIF on this page:

http://phil.ipal.org/tc.html

[Smerity]

Thanks for pointing that example out! I should have searched when I wrote about it, but it just tangentially dawned on me that true-colour GIFs were possible as I was writing the article.

[bluedino]

If I drag that true color GIF in Safari, it doesn't do the drag with transparency like the other two. Weird.