Toyota releases the versions of the OEM navigation hardware as "generations". This is the history on 4Runner:
Generation 2/3 (very similar, and they use the same update discs): 2002-2004
Generation 4: 2005
Generation 5, which included Bluetooth support: 2006-2009
Generation 6, which added a USB port with iPod controls: 2010-?
Depending on the model, Generation 6 may use either a DVD or a hard drive for the map storage. It appears they're using hard drives on Lexus and DVD's on Toyota, but I'm not sure. If you have a hard drive version, then you load map updates via the USB port.