Man, where do I start on these? How about here:
http://imageevent.com/exhibitman/int...ngexhibitcards
The Salutations were not printed through the 1950s, but certain cards were printed for as long as those players were playing, most notoriously Ted Williams, whose card has been confirmed into 1961. The cards of players who were gone by WWII are extremely short-printed and are very, very hotly contested when they come up for auction. Of course, I've long been an advocate of scrapping the distinctions between the "Salutations" and the other postwar cards and treating it all as one big issue with distinct series and levels of difficulty.
Oh, and for anyone thinking of branching into Exhibit collecting, don't do it. Stay with other cards. The 11th Commandment is "Thou shalt not collect what Adam is collecting until he is done with his sets."