For a long time people have talked about how horrible HFS+ is. Most notably, in my opinion, Linus Torvalds (the creator of Linux and Git) who said "Their file system is complete and utter crap, which is scary." John Siracusa also wrote about the problems with HFS+ in his 10.7 review along with talking about it on his podcast, Hypercritical in episodes 56 and 57.

The gist of all this really is that Apple needs a new filesystem. It has been a while since Apple had ZFS support on their website for release in Snow Leopard. After which Apple dropped ZFS support because of licensing issues. There had been talks of Apple developing their own file system, although I think that's the wrong way to go. I think Apple needs to approach file systems the way they approached Safari with Webkit. I think they would be best served by picking up a liberally open source file system, such as BTRFS, or grabbing up one of the ZFS ports and continuing development while leaving it open for anyone to use. One of the great things about this approach is exactly what happened with Webkit and Google Chrome. Google decided to use the Webkit engine to make a product that competes with the main developers of the Webkit project. By doing this with a file system other vendors could use the same implementation and therefore increase development and in turn stability of whichever system was chosen (not to mention compatibility).

One thing is for sure. People who understand how integral a file system is want something modern.