ClamAV 1.0.0 LTS Released
blog.clamav.net
blog.clamav.net
Obviously using up to date software, minimizing attack surface, and using secure configurations are the first line of defense.
But this is a great second line of defense, and it is great to have the code publicly available. Many antivirus programs are actually just spyware.
Cisco has owned an maintained ClamAV (and integrated it into their products) for a while.