I researched this...There are a few tricks involved in this process to make sure that you cure the rock the right way & the die-off period (which is the whole point of 'curing' live rock--to allow all organisms harmed during transit of live rock to die off and remaining organisms to stabilize) ends as soon as possible & doesn't cause any long-term problems. I decided I will spend the extra money to get it cured because I decided I don't want to deal with it, but if you have the time to do it, it seems to be well worth the money saved...
A few things I recall being mentioned:
-When you get the rock, remove all dead organisms, as well as all sponges and macroalgae.
-There are a few types you need to be extra aware of (I believe one is the Chicken Liver Sponge, which dies off over a very long period of time & can cause major problems with tank cycling).
-Run the protien skimmer, powerheads, do daily water changes of 50-100% for first several weeks.
The book 'The New Marine Aquarium' by Michael Paletta details the process to follow.