I've never heard of this before, though I have heard of the Eastern five elements.
Thank you Kenny for starting this thread. I started with a big overview http://en.wikipedia.org/wiki/Classical_element
-- there are quite a few ancient systems out there based on different classifications of "elements". The four tarot uses seem to be the only ones every culture agrees on.
My little understanding of it is that elements represent spirit vibrating into manifestation. Earth is the most dense, water lighter and faster, fire lighter and faster still, air even finer and faster...(then you get into the spiritual elements which are not really elements anymore since they are beyond the dimension of the physical senses) but these are the ones tarot uses.
People can be earthy, phlegmatic, firey, or airheads you know? So the elements also relate to psychological archetypes. I think this is the strategy used in astrology because the 12 zodiac signs are subdivided into these 4 broad personality types, the old healing schools used it and Jung made a study of it...
In terms of reading cards I wonder what is most important to know anyway when pulling say a certain percentage from a particular suit.