Prepared queries in 7.2.x? and stmt caching

Hi!
I am a little bit confused on the new "Prepared Queries" feature in version
7.3. Is it really new? I have been using prepared statements (through ODBC)
in 7.2.x versions for a long time now, and it works fine. Am I using
something that is not supposed to be there? What is the difference on
prepared statements/queries in 7.2.x and 7.3.x?
Is there any caching of dynamic and static (prepared) statements in
postgres? If so, is it done on the server och on the client (ODBC)?
I would be very thankful if someone could explain this to me. Thanks in
advance!
Sincerely,
Christian Bucanac