Apple Macs Beware!
There has long been held the (wrong) view that Apple Macs can't be infected by viruses.
Well, it was only a matter of time and that time has now arrived!
A reported 600,000 machines have been infected by the Flashback Trojan which makes use of a security hole in Java. Apple released an update to Java for OS X 10.6 upwards but many machines had already been infected by that time. If you've got a Mac I'd suggest you check whether it's been infected using one of the free checking sites (eg. flashbackcheck.com) and if you are, then download and run one of the free removal tools such as that from Kaspersky.
More importantly, make sure you've got the latest Java update for Mac OS X 10.6 and upwards. If you're running 10.5 or earlier then you have a bigger problem since there is no fix and all you can do is disable Java (see support.apple.com/kb/HT5241)!