We were interviewing a for a position the other day, when the interviewee made the pretty classic mistake of overrepresenting his knowledge on a particular subject. In this particular case it was puppet/chef, although I've seen it happen a number of times over the years. His resume should have been a warning, he listed a large number of technologies that he knew ... actually far more than he could have known. You should keep your list down to a handful of things that you know really well. Anyway, we've been looking at puppet recently for building our machines and using them for development also and since this was on his resume, one of my coworkers asked him about it. "Oh yeah, I love puppet and chef." was the reply. "Great, where have you used them and what did you like about them? Also, where do you think each is strongest?". "Well ... I haven't really used them in production, more just played with them." Hmmmm... at this point he's not making a very good showing. If you come out that you "love" a technology, then you probably should have done more than "play" with it. "OK, then exactly how did you play with them? Did you run the tutorial?". "Yes, I ran the tutorial". By this time, we weren't even sure that he'd run the tutorial or just read a blog post or something. He probably could have redeemed himself after this (he didn't), but it would have been difficult.
In general in interviews, you don't want to be talking about things you don't know about. You really want to be talking about things that you do know about. If you don't know something, don't put it on your resume and certainly don't say much more than you've "read about it, it seems really interesting, and you'd just love to learn more about it here at XYZ Corp when you start."