Which intentional backdoors? I think I might have missed that one? Though I suppose many larger communication platforms will have back-doors (intentional or not..)
If anyone is interested there are actually more "secret" Skype emoticons that can be found below -
skypenumerology.blogspot.dk/2007/05/squirrel.html
There is also some explanation behind how some of them came about, always interesting to get an insight into such things.