My daughter is into Spiderman and superheroes and rocketships (and thanks to me, watching old, "violent" cartoons like Looney Tunes and Tom & Jerry). She also has Disney Princess stuff, but doesn't really do the whole "dress-up" thing. Her aunt bought her a plastic "tea party" set (the kind with dishes and plates and doilies, not with Bachmann). She mostly uses it to pretend-cook rather than hold parties.
My son cuddles with baby dolls. And with most any kind of stuffed animal, especially any that he sees his sister playing with. He is also near-obsessed with dogs, because it's one of the few words he knows. He will push a car/lawn mower/baby stroller with equal gusto.
My point is, kids really don't have a predilection towards liking certain toys or certain activities at a very young age. What develops later is mostly socialized. And even then, it can be counteracted by their own innate nature or by counter-socialization. My daughter's not a "girly-girl" by any stretch of the imagination, despite having pink everything. She actually prefers playing with the boys at her preschool, because they're more accepting of her interests and play more interesting, active games. But at the same time she's not a "tomboy".
My son is definitely "a boy" in the sense that he is more physically aggressive than she was at this age, and more prone to getting into things he's not supposed to. But AFAIK, he still doesn't even have a conception of gender. He calls me "Mommy" as much as he does "Daddy".
If there's anything that having kids (especially one of each) has shown it's that the evolutionary biology arguments are mostly bullshit. There is some physical difference (aggression levels, for instance) in the aggregate, although not necessarily applicable for every single individual. There's a boy in my daughter's class who cries at the drop of a hat and is utterly passive. But socialization (and in our case, deliberate efforts to avoid gender-stereotypical socialization at home) plays a much bigger role.