FLAC is actually more similar to ALAC (Apple Lossless) in that it is.. lossless. But in terms of compatibility, it's more similar to Ogg. In other words, the format has been around for a while, Apple has its own version of the same with no licensing worries, and there's no direct support.
But it's very easy to throw them into Max or a similar converter and spit out AIFF, WAV, mp4, or whatever you need. http://sbooth.org/Max/
I just had a student in a Logic class show me FLAC - I had known nothing about them. I could not get Logic to recognize them in any way.
Then someone tonight else is talking to me about Ogg files. I've looked into these formats a little and I don't see a clear advantage in using them, especially at this point, where they are far from ubiquitous. Please educate me......
It might they're used for piracy. These two formats I think are "free" to use for the public and if a person wants to put some commercial artist music on a file sharing site, companies like Apple & Microsoft won't come after them for using their audio format for illegal activity