I agree with the PP - if it's the boy's choice, then fine! If it's mom's choice (which I find hard to believe) then it's a bit different.
I'm pretty conservative about a lot of stuff but I have no problems with, if you'll excuse the expression, "girly" boys. Especially if they're toddlers. My son is pretty sensitive, wants to wear dresses (even though we have yet to get him one, but he wishes he could fit into DD's dresses - probably next summer we'll get him one of his own to wear) and says he's a "pretty princess" a lot. He also likes nail polish and lip gloss. He also loves fairies and butterflies - his room is covered in them. He likes dolls, cooking, baking, and gardening. He likes to "help" me embroider and has tea parties.
He also wrestles, he adores trucks and trains and cars, adores playing in the mud and dirt, thinks fire trucks and garbage trucks are the coolest thing in the world, likes sword fighting (not too fond of that one myself!) and tells me he's going to be a pirate and a musketeer. (That is, when he isn't going to be an elephant or princess.) And DD does these things right along with him.
Gender, schmender. They do whatever seems like fun at the time and they like to look pretty in whatever way it seems to them at the moment. Sometimes pretty is about nail polish and tiaras and sometimes it's about fire truck boots. Whatever!
(ETA: We also have long and loud conversations, usually in very quiet public places, about the certain body parts boys and girls have, and how big they are, and which ones daddies and mommies have. Etc. So he's certainly aware of biological differences. FWIW.)