Mothering magazine held a contest to design an international symbol for breastfeeding, explaining it as follows:
The purpose of an international symbol for breastfeeding is to increase public awareness of breastfeeding, to provide an alternative to the use of a baby bottle image to designate baby friendly areas in public, and to mark breastfeeding friendly facilities.
Blogs are virtual, but that doesn't mean they can't be breastfeeding-friendly! Put the icon on your blog too--it's available for use here. Also, the mag's web site has a nice interview with the designer of the winning logo (along with a few entries that didn't win but were definitely worth a look).