Lesbian undertone?

That line confused me a bit, because no one on that island procreated. There were no other children, Diana was the only child and she wasn't conceived and born in the normal way.
She was amazed when she saw the human baby, like she knew what it was but had never seen one. She'd never seen a man before either, but knew what they were, maybe from stories.
So what did she know about procreation?

She could've been referring to Wonder Dildos.

It's certainly been discussed a lot in the WW comic fandom in the past, and Greg Rucka (the current writer) has confirmed it.

Well, for argument's sake, a woman can have pleasure without a man, or a woman. Just by her lonesome and no, guys, she doesn't need dildos either. No joystick at all is necessary.

I think that was the point.

But I certainly have nothing against the notion and it would make sense that some, if not most of them, found love on the island.

There is a woman who seems to be taking it harder than the others when Diana's aunt dies. So... just saying...

Did anyone think if you kissed Dr. Maru on the cheek, then you'd be kissing her lips?

I'd say lesbian overtone lol. It was kinda shown that Antiope had a girlfriend - I don't think that was implied. And I do remember in the comics, a conversation between Diana and some women that weren't Amazons, where they asked her how women survived without men on her island, to which she replied "we don't call it paradise island for nothing" or something like that.

http://ic.pics.livejournal.com/mosellegreen/628917/466871/466871_original.png

Also vaguely remember that Themyscira had a marriage ceremony - and obviously, this included marriage between women. I can't find the link, but I do know it was a conversation Diana and Steve had. He was kinda shocked that marriage between women existed.

I think it was nothing more than a joke in an already awkwardly funny scene. It is possible, though.

Personally, I think Diana got her heterosexuality from her father, and it makes her enough of an anomaly among the Amazons that it's one reasons she doesn't spend much time at home.