In short, if you live in the United States, yes.
I always like to take a look at the search terms people used to find my blog and the heading question as well as "Are Craigslist massages legal?" are two popular ones. Craigslist massages are probably just body rubs advertised in a more subtle way. Most legit masseuses don't advertise there, or at least that's been my experience.
So why is it illegal? You can't pay someone to handle your junk. And calling it compensation of time probably won't go over in court very well. I mean, really, judges aren't stupid. I was also surprised to learn that kissing someone for money is illegal, specifically it falls under the definition of prostitution.
What is legal, from what I've read, though I don't claim to be the authority, is getting nude and masturbating, even in front of someone. So if you want to keep your rub legal, you could always self-service, but what's the fun in that?
Personally, I don't worry to much about the legalitites. I think it's something the police are willing to look over as long as I'm not pimping. And usually by the time I get to the end of the rub, the guy is so turned on, that I think that would someone be a conflict of interest if he were a cop. That's what I tell myself, anyway.