yup, I rock out with my needles where ever I think I'll have to wait for a while. It's weird, I'm living in Italy at the moment so I've had to learn new words to tell people what I'm doing, they've given me some of the weirdest looks, even moreso than in Sydney Australia!
Most of my current scarf has been made on trains, but in Australia I'll do it on my lunch break, in the local starbucks, cafes, wherever.
If they don't like it then they can deal with it, people are constantly doing things I don't like in public, so I have no compunction about knitting if I feel like it.
I've done it in a bar even, but I got shut down by a friend's bf who thought it was rude, he claimed I can't listen when I'm knitting. Uhh... WTF? I can listen better than he can when he's watching sports at a bar, I think it's less rude than that!
Don't you wish people would mind their own business? if it's not harming them, then why should they care?
I should say that i've also had some people come and tell me how much they like what I'm making, or who are frankly just curious and interested in a flattering way, so don't be shy about knitting in public