Most Animated gifs do fit in our space requirement, remember most of our users are still on dialup.
Also we have found that some Animated gifs show up as black boxes instead of an actual picture, there is no rhyme or reason for this. So instead of trying to support people on thse issues we have decided that Animated gifs are not officialy supported.
That being said anyone is welcome to "try" uploading one but we can't tell you if they will display correctly or not. AD e won't try supporting you if they dont.