Heres a work around I stumbled upon today:
Go to folder Applications/Cutting Master 2 1.80/Program/Cutting plug-in
Make alias on desktop.
Go to folder Applications/Cutting Master 2 1.80/Program/Cutting Master 2 1.80
Make alias on desktop.
Launch Cutting Master 2 1.80 via the alias
Select Artwork in CS5 and click on <Cutting plug-in> alias on desktop and all should be cool.
Oddly I got it working earlier within CS5 but I have tried reinstalling, moving folders around etc.
Will advise if I get further.