You can see if a program is using Rosetta buy doing Apple Key+I for the information tab and under the "Kind" it will tell you if it is Universal or PowerPC. If it is PowerPC then it is going to run under Rosetta naturally.
I thought the beauty of Rosetta was that you would never know or have to know that it was running. I think its an on the fly emulation not a process, so if you aren't running PPC binaries, you aren't using Rosetta.