I have an interview coming up with a company that I interviewed with 2 years ago. I didn't get that job and wasn't sure whether or not to bring up the experience. It's a large organization so they no doubt have a record of my previous application. The hiring manager for this position was not the previous hiring manager although he was one of the people I interviewed with. When/how/should I mention that we've met before during a past interview?
Let sleeping dogs lie
Unless the manager made a particularly strong impression on you last time (in a positive way), or vice versa, I wouldn't mention it unless the manager raises the issue. I'd be concerned that I had made a poor impression last time, and wouldn't want the manager remembering anything negative. If the issue does come up, you can say something positive like "I was so impressed by your company the last time I interviewed I couldn't pass up another opportunity to try for a job here", but bringing that up out of the blue seems a little... overenthusiastic.
Don't forget that you're in a stronger position than other candidates: based on your previous experience (and, if you're lucky, some feedback from last time) you should know more about what the company (and hiring manager) want out of a candidate, and should be able to tailor your responses to what they're looking for. Take any benefit you can get.
Good luck.
Take it as a good sign
If this hiring manager interviewed you before, you can probably assume he was impressed with you. Maybe the other position wasn't the right fit for your background, or they liked you but found someone they like a little better, but I'd recommend you approach this interview as if you had no advantage, and be prepared to sell yourself as such.
A couple of cautions. First, there could be danger in bringing it up first -- if the manager doesn't remember you (small chance, but possible) -- talk about a wet blanket to throw over the conversation. I guess the interviewer could also be waiting for you to bring it up, but in my mind you have more to lose and very little to gain. However, I would recommend being prepared with something to say in case he brings it up. I agree with Matt: "I was so impressed by your company the last time I interviewed I couldn't pass up another opportunity to try for a job here" might be too vague and therefore not seem authentic. But you could say something specific like "last time we met you mentioned your team was responsible for the XYZ product launch, so it appeared to me your team had some exciting things going on." Just enough to say you remembered him, and you're excited by this opportunity (which you would do in every interview) -- nothing more.
Also, don't turn the conversation into what was going on two years ago -- you just want to send the underlying message that the interview was memorable and you were impressed enough to come back. Make sure your comments keep to the topic of how you now meet the needs of the current role -- anything else is time not well spent.