Question: What is a Journaling file system?

Even wikipedia doesn't give much information. Apart from NTFS which other file systems(on Windows / Linux) support journaling and how does it give a performance boost?

Answer: 
A journaling filesystem records changes to the filesystem before it actually performs them. In this way it is able to recover after a failure (e.g. power fail) with minimal loss of data.

The [Features](http://en.wikipedia.org/wiki/Comparison_of_file_systems#Features) section of Wikipedia's comparison of filesystems gives which are journaled.

Journaling does not give a performance boost. In fact, the journaling operationn reduces the speed slightly, in exchange for the above reliability.
A journaling filesystem is a term being misused widely for filesystems that are not, after all, journaling.

What "journaling" means in the context of filesystems is that the filesystem is capable of recovering from crashes and power losses to a consistent state. It does not mean a performance boost, it doesn't mean that the filesystem recovers to a complete snapshot some time before the crash, it doesn't even mean that there wouldn't be a "filesystem check" style operation to recover after a crash.