Real world scenario: untar and cat
Its time for some more pedestrian tests now. For example, what is the fastest filesystem when untarring the vanilla Linux kernel 2.6.36? 
Don't be fooled by XFS low CPU usage, as it is the slower FS by a very great amount. All things considered, the best FS seems EXT4: its speed is on par with EXT3 and BTRFS, while using lower less CPU time. However, apart XFS, all FS performs about the same.
However, this test is surely influenced by features as caching and deferred allocation. What happens when we issue a final sync?
We can see that XFS continue to be the slower FS, with EXT3 also performing slower than EXT4 and BTRFS, which is the fastest FS by a very small margin.
What about catting all the extracted files?
In this read-bound test, EXT3 and EXT4 show not so good results. In contrast XFS and especially BTRFS are way faster. However, the latter has a quite high CPU load, so XFS can be preferable here. Note the somewhat higher BTRFS's system CPU time: it contribute to prove that this filesystem has a quite complex metadata scheme.
UPDATE: preparing the system for another benchmark, I noticed that, in contrast to what written in Fedora 14 documentation, write barriers were non enabled on EXT3 filesystem. Please read the updated "Conclusions" page.