PS3Hax member ricardopvz has released ports for PSGrade for Arduino Duemilanove/Mega. If you have been under a rock for 24 hours, PSGrade is a new method to downgrade your PS3 and enter it into service mode. Please see the various news posts related to PSGrade before attempting to do it.

[Download PSGrade Arduino Arduino Duemilanove/Mega Ports]