Since I have not "installed" Rosetta on my iMac and EasyFind turns up no file names containing rosetta, I would guess you have installed Rosetta at some point. Someone else may know a command line trick to determine if it is installed but the only way I know of is to attempt to launch a PPC app. (You can tell if it is PPC by doing a Get Info on the application file and under General the first item on the list is Kind. If Kind is Application (Power PC) then it will require Rosetta to run. If you launch it and it runs then Rosetta is installed. If Rosetta is not installed then you will be prompted to install it.
