By default, Mac OS X does not support Trim for 3rd party SSDs. This is not a major problem, as people have developed tools to do it (Trim Enabler being the most common). However, every Mac OS X Update disables Trim Support and you have to manualy re-enable it.
A couple of days ago, after I upgraded the OS of my Mac Mini to the latest release (10.8.3), I tried to re-enable Trim Support for my Samsung 840 SSD but I found out that Trim Enabler wasn’t working any more. Not willing to wait for Trim Enabler to be updated, I searched for an alternative. I found Chameleon SSD Optimizer, I tried it and it works!
So, if you want to enable Trim support for SSD in Mac OS X 10.8.3, your best chance is Chameleon SSD Optimizer!