Kaspersky warns of cross-platform virus proof of concept - Computerworld

"Though rare, this is not the first instance of such a virus appearing in the wild. In 2001, the sadmind/ISS worm exploited a hole in Sun Microsystems Inc.’s Solaris to infect systems running vulnerable versions of the operating system. Infected systems then scanned for and attacked servers running Microsoft Corp.’s IIS Web server software. That same year, another proof-of-concept virus named Winux infected both Windows and Linux systems."