Ah, thank you daradude! I corrected the spreadsheet and chart. I misread the descriptions when putting the list together; thought there was a built-in port expander but just reread the info and looked through the schematics-- the pins are all native ATmega645 pins!
@westw: Thanks, good suggestion about adding PCBs. I was really just trying to find all available variants and their features, though-- would rather spend time coding than revising the spreadsheet 