I haven't seen one yet.
BTW: Flash will still overheat and stut off if you push it too hard.
5DMKII - 7D Dual Body Bag - Go 'L' and don't look back!
Got 7D? See http://www.usa.canon.com/dlc/controller?act=GetArticleAct&articleID=3167
Thanks Phil. Would be purely for convenience of not having to purchase so many batteries for small indoor shoots, and I guess recycle time would be better. Obviously I could get rechargeable batteries .. but those need to be charged.
Canon 5D Mark III