As others have said, I typically get the "Nice camera!" comments, to which I respond "Thanks". Usually that only happens when I have a white lens on. If a shooter shows a genuine interest and I have the time, I have no trouble talking the why's and wherefore's of my kit. I usually get some insight on their choices as well.
I had a memorable moment at a music festival I shoot. I saw a photog toting a DSLR with a large black tele (think 300mm 2.8 esque) through the crowd. I was shooting with my wide angle at the time, so I mentioned "Brought the cannon out, hey?", doing my part in small talk. His response, which I doubt I'll ever forget was, "It's not a Canon, it's a Nikon!". Took me a second to see my unintended pun, and I'm not sure he took it as such and was clarifying, or just thinking he was one-upping me. I wasn't interested in starting a gear debate, so left it at that. I thought it was pretty funny nonetheless.
If I see someone I'd like to chat with, I make sure they're in an idle mode before I approach them, out of respect.