The Sourcefire Corporation has acquired the open source product ClamAV. ClamAV is a fairly user friendly and very well supported anti virus tool for the open source market. While the product hasn't seen much praise or attention, it serves as a pretty good competitor to commercial products by being an integrable component of an open source firewall and/or Intrusion Detection System. ClamAV often touts that it has fixes to virus's several hours and sometimes days ahead of the higher priced commercial competitors. I myself have built several personal use IPCop firewalls with ClamAV for gateway virus scanning.
Sourcefire hopes to make this open source product marketable and improve it's commercial successes. It also promises to maintain the open source nature of the product. Sourcefire has had successes in this same area with Snort, the Intrusion Detection System.
A full press release is available: here