After the discovery of a hacker intrusion, Sony's PlayStation Network has been down for more than three weeks. The company hasn't been able to definitively state whether users' credit card information was compromised. But in a letter sent to game publishers, Sony writes that it's seen no proof that such data was hacked.

In the letter, leaked to IndustryGamers.com, Sony's senior VP of PR tells publishers and developers: "As of this writing, there remains no evidence that the credit card information was stolen and the major credit card companies are still reporting that they have not seen an increase in fraudulent transactions due to this event."

The letter also details some of the steps Sony is taking to (hopefully) prevent a breach like this in the future:

• adding additional automated software monitoring and configuration management to help defend against new attacks;
• enhanced levels of data protection and encryption, as well as additional penetration and vulnerability testing;
• enhanced capabilities to detect software intrusions within the network, unauthorized access and unusual activity patterns;
• implementation of additional firewalls;
• expediting a planned move of the system to a new data center in a different location with enhanced security; and
• appointment of a new Chief Information Security Officer.

Sony also confirms that it will offer "welcome back" packages—including free downloads of "selected PlayStation entertainment," 30 days of free service, and service extensions for however many PSN services were unavailable—to customers once the Network is up and running again.

PlayStation Network: Here's The Official Letter Sony Sent to Publishing Partners [Exclusive] [IndustryGamers.com]