Here's some great news for PS3 owners who don't want to update their consoles to firmware 2.70 but still have access to the PlayStation Network.
A Spanish hacker named Bakke has come up with a way to access the PSN even when you're on a lower PS3 firmware. You can still browse and buy stuff from the PlayStation Store, play around in Home, and play with your friends online without having to update to 2.70.
Bakke's trick works on Sony PS3s with firmware 2.30 and up. All the instructions and pertinent files are available at the source link. The original page is in Spanish but you can read the translated instructions here.