My dd has always been pretty friendly, but it depends on the stranger. The stranger has to approach her the right way (no touching, not in-her-face, etc.) and kind of "flirt" with her first from a distance. She likes it if the stranger is REALLY happy to see her - genuinely big smiles and coos at her from 5 feet away or so. Then she gives a return smile, and the stranger can come closer.
But if someone doesn't respect those boundaries, or talks to ME instead of dd - i.e., "Oh, what a cute baby," and then touches dd or leans their face in - no smile! Occasionally she even starts crying. Also, it's like she can sense someone who feels awkward around babies - she doesn't like anyone like that. She gives them the "wary stare."
Dd also loves all babies/children and always wants to touch/talk to/smile at other kids.
Julia
dd 11 mos
(I'll be one year old tomorrow!
: )