ClamAV is generally configured to automatically update its list of virus definitions via the Internet.
Linux
IPCop is a Linux-oriented network management solution and Copfilter is an add-on which implements ClamAV as well as other security additions.
Mac OS X
AppleMac OS X Server has included ClamAV since version 10.4. The anti-virus scanning is used with the operating system's email service. Additionally compilation assistant programs Fink and MacPorts have had the ability to install ClamAV as well. Counteragent software from Jett Fuel Productions implements EIMS based email service using the ClamAV service to scan email for viruses on Mac OS X. Graphical Interface front ends have been created for implementing Clamav for end-users on non-server Mac OSes and include ClamXav and Tiger Cache Cleaner (see links below.)
ClamWin is a graphical user interface version of ClamAV for Microsoft Windows. Features include on-demand (user started) scanning, automatic updates, scan scheduling, context menu integration to Explorer, and an add-in for Microsoft Outlook . To provide on-access scanning (scan when a file is read or written), the free softwareWinpooch or free proprietary Tech-Protect must be used. A plug-in for Firefox which uses ClamWin to scan downloaded files is available here.
ClamXav is a free (but not open source) port for Mac OS X which includes a graphical user interfaces and has a "sentry" service which can watch for changes or new files in many cases. There is also an update and scanning scheduler through a cron job facilitated by the graphical interface.
Tiger Cache Cleaner is a shareware software for Mac OS X which installs and presents a graphic interface for using Clamav to scan their computers as well as other unrelated functions.