I'm a little late on this Flashback scourge infecting the internet. As recounted on the TenFourFox development blog, it's a virus that takes advantage of a weakness in java to gain access to your system. Apple has a patch for this, but unfortunately it's for Snow Leopard and up, so PowerPC users are left to the wolves. The good news is there's no evidence Flashback has been compiled to run on PowerPC computers, but that won't necessarily remain true, so in order to keep safe you need to disable the java plug-in in all your browsers. In the preferences for Camino and Safari, there's a checkbox you can uncheck, and in TenFourFox, if you have plug-ins enabled, go to the add-ons manager and click the disable button for the java plug-in. I briefly looked into removing java system-wide, but read indications that it would involve extensive surgery and that it wasn't really necessary anyway. But this is a serious threat, so it's highly recommended you disable java in your browsers (Leopard users can also open Java Preferences in the Utilities folder and disable java applets).
In other news, apparently there's a twelve percent chance all our motherboards are gonna be fried in an apocalyptic solar storm by 2020, if you believe the prognosticators. Something like this actually happened before in 1859; there's all sorts of fascinating reading on the Carrington Event. The only thing electronic in the day was the telegraph machine and there was much mayhem. Fortunately if something like that happened again, we'd have at least a few hours warning, so we can all rush and turn off our electronic devices before the storm arrives. Although I'm not sure what people are supposed to do if they have those cars where the computer system is always on. Hello, $30,000 brick. Anyway, the point of all this longwindedness is to say it's probably a good idea to back up your data not only in the cloud but on physical media, too. It doesn't take long to burn a disc and it's good to have peace of mind. And it's not only solar storms after servers. It's also hackers, and they don't wait 150 years between major events.