Hi there, I just read a similar message by user Paolo (which had registration problems as source) but I think my problem is different since I am registered at NI already.
I was migrating from my G4 last night to my new Intel Mac/Leo 5.6. Installed GJBB off of DVD, installed AU components as well. BTW, installing other plugins succesfull (ie, Bandstand) but the GJBB plugin doesn't show up in the audio units manager window of Logic 8. I restarted Logic and the machine already.
Funny cause on my G4 everything went fine, also using Logic 8 there. All components in the same place.