Product review (4 stars): no more leaks!
After fighting with an old leaky gasket (and after already paying a repairman to fix it!) we finally got the right gasket and installed it ourselves.  Happy to say we haven't had a problem since then!  You do need to take care to make sure it is the exact one for your dishwasher, as there are some similar but not quite right.  Also be sure to install it with the correct side in, as it will definitely not work if put in backwards.  There were no instructions with the gasket, so we had to find that info online for our exact model.