You guys probably all set your clocks forward from 12/31/99 to 3/1/10 after the bug hit you. That span of time is ten years and three months. So you set your clock forward ten years and three months. Then, when your system clock suddenly came back on the map and was readable by the PS3 OS, it started adding those same ten years and three months you told it to add to a date from 2010 which it actually knew how to interpret, resulting in the sum of those two dates being 4/29/20.
Basically, all the OS clock is, is a number that you either add or subtract from the system clock to make it into the exact right time. When you set the time on the OS clock, you're changing that number, but you're not affecting the system clock, which continues to tick on and on unless its battery dies.
