After quite a bit of "googling" around, I believe I've identified this as Parides iphidamas whose common names are Pink Cattleheart or Transandean. As near as I can tell from having studied several different web sites and images, this is a female of the species.
There seems to be quite a bit of variability in the coloring and markings of this species and I'm by no means an expert! So I trust someone out there will correct me if I've misidentified this one. :-) It is resting on a Pentas blossom cluster... and I do know that Pentas blossoms are a favorite of butterflies everywhere they bloom so have vowed to have more of them in my garden in 2011. (Unfortunately, they are an annual flowering plant and are fairly expensive but I simply must find ways to attract more butterflies to my garden and don't have the room for a butterfly bush!)