I know.
I also saw some people have uploaded the gifs.
So, I also challenged it.
RS say, "You can upload gif" on the manage page.
However, my gif file was refused.
Size was proper.
I do not know the reason which cannot be uploaded.
Maybe, I feel that we can't upload by the manage of RS now.
However, We will be able to upload gif on Description by html code.
I use it. *compromise*
http://sarangallery.rubberslug.com/gallery/inv_info.asp?ItemID=366899
And, If you find that how to upload gif by manage of RS, Please teach me too.:D