A Trojan prototype on OSX ?

Netusers on Macrumors forums got tricked by a file supposed to contain screenshots from OS 10.5. Once double-clicked, this archive file called latestpics.tgz expands into an executable file under the shape of a picture. Compiled for PowerPC, it cosily nests itself in the system, infecting other applications (however this piece of code doesn't work and keeps the app from running) and trying to send itself through iChat.
In short, nothing very serious, but that Trojan prototype comes out as the first on Mac to replicate and send itself, although iChat is definitely not the most efficient way to do so. It also requires the user's action, who first has to open the archive and then double-click on the resulting file.
It is only a matter of time before such trojans/viruses begin to appear on our platform. And the more famous OSX becomes, the sooner this will happen. This might be the reason behind Apple's silence concerning the absence of viruses on Mac so far: they wouldn't want to be discredited when this eventually happens.
Ambrosia's president has published more detailled information on his website. A good read.