It's a 'gamers' benchmark which is meant to stress your system as a measure of how powerful it is. In reality it's not really the be all and end all. In fact it often doesn't mean a lot other than how well your machine can run it (not an actual game).
I've always loved using it, but only as a guide for building/overclocking. Searching for huge scores in 3DMark is sometimes pointless if the games you play aren't going to stress the system as much as the benchmark itself. Although of course, it gives you a good idea.
Traditionally the cycle goes;
New version of 3DMark = tiny scores for everyone.
Then people start getting big scores.
Out comes new version
All good fun and quite entertaining in small doses. The only thing that really matters is the performance of the games that you like to play
