I do know someone whose daughter (the same age as my daughter = 3.5) is named Lucy. That was the only Lucy I knew of in real life until recently when I heard it at my kids' music class on a child who was visiting that day (younger than my daughter, maybe 2 years old). When we first started thinking of this name (back before my daughter was born), I hadn't heard it at all in real life.
I am happy to hear a few people say that you don't think it will become a top 10 name... I am just so picky with girl names and felt like my daughter's name (Georgia) was the perfect combination -- (1) a name we loved and (2) low (300s) in popularity. If Lucy was that low on the list, I'd be equally thrilled!!