Gil - can you link me to the user groups you are referring to? I'll ask some mac hacker pals about the virus and Lightroom questions...
EDIT - sorry about the double post - got lazy.
Gil - have a look at the links below...
This one discusses Leopard compatibility. Note the link on the last post and look at the chart. Nutshell...lightroom - known issues but plans to fix are in the works.
More good info here... Not able to find out much on a potential virus. Any more info Gil?