The 2010 systems have a totally different USB interface and no CF input instead of the iPod/CF of the 2009 systems. The Nav unit also has a better (higher resolution?) screen.
There isn't an upgrade path without replacing all the hardware.
Updating your maps requires purchasing a code from NavTeq and paying your dealer to install the upgrade:
NAVTEQ - Maps for your Nissan Navigation System
I am going to wait another year to do it.