via the Gran Turismo website. You could be earning money at work right now.
In addition, the patch allows tracks from the Course Maker to be used in online races, which also dole out more experience points. Gran Turismo 5 v1.6 supports multi-monitor, multi-PS3 setups, and claims to have optimized the speed at which games are saved. It's a significant (and free) update, so be sure to have your assistant read the full documentation and report back to you.