I installed the plugin via the "Add new" dashboard plugins page, when I tried to activate it said it could not be activated due to a fatal error and to please chmod 777 wp-content/w3tc. At that time wp-content was 777 (owner me:group web) and wp-content/w3tc did not exist. So I tried creating wp-content/w3tc and chmod 777. Then when I tried to activate the plugin it came back with the same error and when I checked the directory wp-content/w3tc had been deleted.
I tried this whole process a few times, deleting the plugin and following the installation instructions very carefully, same thing every time. w3tc is not created, but it asks me to chmod it. If I create it, it gets deleted upon attempted activation.
Then I tried installing the plugin manually via FTP, same thing.
I've asked on the forum with my host (NearlyFreeSpeech.net) because they do have a different server set up to more commonly used hosts (they run freeBSD), but I don't know if I'll get any insights. Other than that I'm using PHP 5.2.