Right, both of those have a section on 'submissions', the US Games one wants the cards in a certain size and certain format, so read that first before starting. They're not too eager for black & white decks, preferring color ones instead. Both places want to keep the originals also, for reprints, if accepted.
HOWEVER, not all decks get published by professional tarot publishers, so if those two don't work for you, don't give up. A bunch of people on this list have decks out, and I know Mr. Rosales who did the Hello Kitty deck just has them photocopied at the local printer when he needs more (so you can get high end and low end, and everything in between). Lo Scarabeo, unfortunately, doesn't take solicitations, all their decks are done with their own group of artists. And AG Muller (I think I spelled that right) concentrates on historical decks.
Check the archives on this list, there's a lot of info on publishing, who to contact, how to do it yourself, etc. to give you some basic information.
As far as publishing, the other responses have already given you plenty of food for thought.