I understand that there will shortly be an automatic and unavoidable upgrade of all Version 7 installations to Version 8. I am currently using Sophos V 7.3.12C on a number Snow Leopard and Lion partitions with good results. Please watch this space for further announcements as the launch of Mountain Lion gets closer.
Thanks for using Sophos Antivirus for Mac Home Edition! Home Edition users currently running v7.x will be automatically upgraded to v8.x during the month of July. There are no plans to make v7.x of Sophos Antivirus for Mac compatible with Mountain Lion. This will not affect automated updates to existing installations. Customers currently running our product on 10.4 will continue to receive updates and upgrades as usual via the AutoUpdate process. Starting with v8.0.5 of Sophos Antivirus for Mac Home Edition it will only be possible to perform a new installation on OS X 10.5 and above. Unfortunately this process is not compatible with version 10.4 of OS X. This will ensure compliance with the new Gatekeeper functionality, which requires that the digital signature for any software downloaded from the Internet is based on a certificate from Apple. The most significant change is that the installer for the product will be signed by Apple. We fully expect this new version to be available in time for the release of Mountain Lion. These changes will be implemented in the July monthly release of Sophos Antivirus for Mac, which will be v8.0.5. While the product works well on the new platform, we have found that there are a few changes required to support Mountain Lion fully. Sophos has been actively participating in the pre-release developer programs for this new OS version. Earlier today, Apple announced that a new version of OS X, codenamed Mountain Lion, would be released in July 2012.