Can the free Mac edition detect for keyboard loggers of any type?
please see this post http://openforum.sophos.com/t5/Sophos-Anti-Virus-for-Mac-Home/PUP-Commerical-keylogger-detection/m-p...
Hope this helps.
To answer the other half of the question, yes.
If the keylogger is malicious in nature and not a commercial program, it will be detected as malicious.