The LSB is a long-running attempt to create standards to encourage portability between Linux distributions.
The Filesystem Hierarchy Standard test is the first specification delivered by the LSB (as far as I know). They note that These are unapproved test suites and issues remain both with the test suites and the specifications under test - so don't be too hung up on the results.
Having noted that, lets look at the results. Ten major distributions were tested, with SuSE 7 finishing top (238/243 tests passed) and Debian (Woody) second (226 passes). Redhat 7 was only 3 passes behind Debian (something of a surpise to all the RedHat conspiricy junkies, I suspect), while Caldera OpenLinux eServer and Mandrake 7.1 finished last and second-last with 199/243 and 200/243 tests passed respectivly. Slackware and Debian-Current were probably the major omissions from the test results.
The unfortunate fact is that I suspect this test result is fairly meaningless with regards to the future of potential distribution portability. It is much simpler to create a standard file hierarchy than many of the other challenges that face the LSB. Still, it is a step in the right direction.
(Also, I couldn't actually see a link to the actual FHS Spec. Perhaps some fresh eyes might find it.)