It's not freeware, but DreamQuest has an awesome Spades game. There is internet multiplayer available, too, which is very cool (and very easy to use). It will show you games and you can choose which one you want to join. The only downside is that you cannot be a host using a PPC - only PC users can, but you do get to play against PC users, Palm users and other PPC users. It is a lot of fun.
Here is the
link.