I'm more the low profile guy like Who Dares Wins talks about.
I think it's a good policy at work.
People have to earn my friendship or aquaintance. I'm a nice guy and not snobby at all, but reserved. I get to know people over time instead of some kind of instant connection.
Notwithstanding, I like what FairShake is saying. It wouldn't hurt me to open up a bit more with more friendliness.
I think the reason I'm reserved besides being an introvert and growing up in New England (a region never known for friendliess save parts of Maine, Rhode Island and parts of Boston) is that I'm a bit cynical about the clique stuff.
From 6th grade all the way up to recent days in the workplace, I see how clique-y people are. You can be as friendly as you want, but if you aren't part of their group, you will never be truly included by them. (Read the "Embrace the hate" thread to see what I mean.)
So I have nothing against being more friendly, in fact, Im working on that, but I don't expect anything from it.