List of currently supported Epson Printers for OS X:
• Epson Stylus COLOR 740, Stylus COLOR 740i and 740SE
• Epson Stylus COLOR 760
• Epson Stylus COLOR 777, Stylus COLOR 777i
• Epson Stylus COLOR 860
• Epson Stylus COLOR 880, Stylus COLOR 880i and Stylus COLOR 8 cubed.
OS X has few "Built In" drivers for peripherals. Everyone has been dragging their feet on OS X possibly in anticipation of MW. For this reason........you can purchase any printer you want and it will work in OS 9.1. Since you should be able to dual boot to either OS X or 9.1, drivers for OS X will not be an issue unless Epson never develops a driver for it which would be pretty stupid on their part.
You could also step up or back a model to get one that will work in OS X. I know the 780 has some good prices now though.