The Sony PS3 problem is not solved yet, but Sony identified the issue and says it should be fixed in the next 24 hours. As reported earlier, old PS3 consoles cannot log into the PSN network and also offline game play is affected. Sony reports on the Playstation Blog the problem is being caused by a bug in the clock functionality incorporated in old (fat) PS3 systems.
The new Slim PS3 consoles are not affected by the bug.
Sony advises you to not use your previous generation PS3 system, as doing so may result in errors in some functionality, such as recording obtained trophies, and not being able to restore certain data.
Sony fixed the PS3 bug - or better - the bug fixed itself by changing the date to March 1st. The old PS3 unit thought that the year 2010 is a leap year for some reason. Because of that it set the date to February 29th. If your PS3 is still not working you can set the date manually to March.