That's a tough question to answer, but one which we wondered about last year as well...One of the reasons why it's hard to answer is that you never know if you are actually a second-wave interviewee (although you usually have strong suspicions based on timing and hearing other people interviewing there much earlier) or if the program is just slogging through their applications and got to yours later. Of course, in the Internet age where information travels fast and far, you can usually piece together that certain programs have offered initial waves of interviews, second waves of interviews, etc...
To answer your question, I can't say I know of or heard anyone matching at a program where they were a "second-wave" interviewee, but I'm pretty certain it happens. It's a match, after all, and anything can happen (i.e. Fred Hutchinson having an unfilled spot last year). No one knows, or ever will know, how this whole process works, so I would say if the program is somewhere you're interested in going, no matter how late they offer you an interview, I would strongly consider going - if only to check the place out for your own curiosity. You never know - you may end up there after all.
From a personal standpoint, the only interview I got that I am 99.999% certain was a "second-wave" interview was UCSF (offer in March, interviewed early April), and they seemed totally uninterested in me for the entire time I was there....which left me wondering why the hell they invited me in the first place. Just a horrible interview experience. I didn't rank them, so I have no idea if I'd have matched there, but based on my interview day, I am quite certain I was nowhere near their final rank list of candidates. I think their program was really good and I absolutely love San Francisco (who doesn't), so I don't hold it against them at all.
Anyway, that's my input from last year's interview circuit...Take that for whatever it's worth...
