On my C2D Intel 24" iMac, 10.6.1
I installed this rascal without problem, but I see no improvement. All was dandy before. I suppose this is because an R340 is "old", and Apple/Epson somehow thought it (too) qualified for a generic update.
If Apple, or Epson, were on the ball (IMNHO) they would have included a list of N/A machines and ergo, Software Update would not show this as required.
Apple Epson Printer Drivers
Snow Leopard printer drivers.
Version: 2.1