I had two phone interviews over two weeks, the first with the position manager, the second a shorter interview with the co-CEO. The first interview was a fairly normal getting-to-know-you kind of interview that seemed to proceed reasonably well along normal lines, mapping out where there might be a fit on both sides and where I might be able to contribute most.
The second interview, ostensibly focused on cultural fit, didn't set off any particular alarm bells for me, either, but that opinion clearly wasn't shared, since I literally never heard from them again (even to indicate that they've moved on), despite trying to follow up a couple of times.
In any event, both of the interviews themselves were pleasant and in both cases, I learned quite a bit about the company; I just thought the lack of communication in deciding not to make an offer a little abrupt.