That will not work. You can do the same thing on a PC with the IPod but because of the software on the IPod you cannot take anything off the device unless you have software on the PC.
I'm fairly certain it would work. I really think I did it on my friends' PS3 when he just got it...
Normally, if you just select the iPod Device from the music menu, it will not show you any files... but if you hit the triangle and select display all, it should give you the option to copy over the iPod Control folder. PS3 software is based off of Linux, if I am not mistaken, and as long as the iPod is formatted for FAT32, the PS3 should be able to read all files as long as you go through the "Display All" dialogue.
Of course, as you said, I could be wrong... but it's worth giving a try!
And any DRM-Protected files will not play on the PS3, I know that for sure... but any AAC/MP3 files that you ripped yourself should work just fine