I WAS running Photo Mechanic version 4.6.7 and I run Mac OS X 10.5.8 on my Intel-based Mac.
Today I downloaded the new PM 4.6.8 and - as on previous updates - dragged to the Applications folder where it overwrote the previous version. It now appears that version 4.0.8 is only for OS 10.6. or later. Annoying to be told after installation.
On opening PM I now get the message that I need the earlier version... but I can't find a 4.6.7 version on the archives page. So, any ideas for restoring version 4.6.7 please?