Now with the PS3 Firmware 3.10 update you can send an error report to Sony.
I encountered this personally just yesterday when I was playing Modern Warfare 2 and think its a good feature for future PS3 Firmware updates to reduce issues.
To quote: "Thanks to firmware 3.10, Sony now allows users to send an error report after an improper shutdown.
Freezing is an annoying issue and there is no way for everyone to be able to report such errors in an easy way. While it's unknown what exactly is being sent to Sony, expect information about your software and hardware to be sent.
According to a disclaimer before sending in the report, this includes PSN account information, the content saved on your PS3, and your email address. This information will be sent if it was being used during the time of the problem."
More PlayStation 3 News...