Did you ever get to the bottom of this? I asked my host to install the imagick PECL extension purely so I could have animated avatars, which they kindly did. I went into my ACP and sure enough the "ImageMagick PECL Extension" option was selectable (whereas before it was greyed out), so I selected it and advised my users they could now upload animated GIFs as avatars. A few have tried, however, and none have worked.
Is there something else one has to do to make it work?
Thanks.