Mark Allan has released ClamXav 2.6, which updates the ClamAV engine to version 0.98. ClamXav, Sentry, and the ClamAV engine are now 32/64-bit, and ClamXav now requires Mac OS X 10.6 Snow Leopard and an Intel processor. The release also adds compatibility with Notification Center on 10.8 Mountain Lion for ClamXav (but not Sentry), fixes issues with unnecessary reporting of quarantine folders and updated virus definitions, adds a timestamp to logs of scheduled scans, and makes improvements to the French, Italian, and Czech localizations. Shortly after the 2.6 release, 2.6.1 was released with a fix for 32-bit machines running Snow Leopard. (Free, 19.8 MB, release notes)
Mac OS X Zip Expanding Utility
Firefox (and possibly other applications) may ask you what you want to do with .zip archives that you download from the Internet. If you want to expand them with Mac OS X (rather than StuffIt Expander), you may be unsure of which application actually does the job. You're looking for Archive Utility (in Leopard and later) or BOMArchiveHelper (in Tiger). In either case, the application is stored in Hard Drive/System/Library/Core Services/. Don't move it from there, though, or you'll confuse matters.