I have never once used interest but I would still equate "pin" to that site. For that reason I would steer clear of that language. It's a pretty well branded verb and I'd rather not be associated with that site. edit: My wife suggests making it look like a sticky-note. Also, without any prompting she said that "pin" was way too pinterest like.
thenewgreen, I respectfully disagree. I don't think we should let popular sites determine what's best. What you're saying is the equivalent of wanting to change the tags on Hubski because it's too similar to Twitter. Also, a small identifiable sticky note icon would be hard to design while still appearing pleasantly on the site. A yellow square just wouldn't look the best, I'm afraid.
Perception is reality and in my case I see the action to "pin" something as being decidedly more proprietary than "tagging" something. "tagging" is a now ubiquitous action done across a wide network of sites. Perhaps "pinning" is too and I'm just ignorant of it. -Not an unlikely thing. I also just like the term "sticky" way better. It was immediately what forwardslash called it and it just seemed "right". You want that post to "stick" around longer. Makes more sense to me.