When you log into the game today, and if you're updated to the latest version, you'll hear a modem sound ring across your speakers. This is a joke, this is only a joke, and you have no need to be alarmed.
We've gotten many tips in about this, mainly people thinking that it's the Confiker virus which was supposed to start today. Well, it's not. And from the look of things Confiker is bust too (at least for now). So you're safe and okay, and can be angry that you've been had by an add-on author. Or just laugh about it, which is what I've done.
The author has even come out and said this is a joke, and is offering an apology to anyone upset by this.