To display correctly an animated gif image just use the "edit html" link and paste the following code where you want the picture to appear:

<img src="picture_name.gif">

You can also place the picture using GPC, press the "edit html" link, look for the code of the picture and remove the part right after the .gif (something like "picture_name.gif/picture_name-full.jpg")

Example:

(You can see another example working in a Google Page at:
http://viagensdojoao.googlepages.com/test2 )

THIS should be the DEFAULT behavior when adding any GIF