a f/Friend posted a question about this on his facebook page today, and I think maybe it's worthy of some chatter on my part. I was surprised at how many responses there were, without one being at all like mine.
I used to use this phrase more for myself, about ten years ago, when it didn't feel quite so cliched or flaky. I wrote it in a personals ad (of all places, how embarrassing!) of all things, and explained it as, "anti-dogma, pro-awe" - which probably is a better all around phrase, and unlikely to catch on and become overdone.
So, for me, "spiritual" is, or has been, a way to say, I experience something that feels like God (being atheist, I wouldn't actually name it god, at least not without extensive hedging) - I get that, I'm part of it (it being creation, lifeforce, mysticism, I"m not even sure)
and "Religious" is tainted with, essentially, for me, well, believing stupid things. I was trying to think of a better way to say it, but that's not my gift, so there it is.
If you're religious, maybe you believe the pope when he says that condoms are the enemy when combating AIDS. This essentially goes against reason, logic, and, well, reality. But if you're that kind of Catholic, he's right because he's the pope.