I asked about LightZone in the "Other RAW Converters" forum, since it wasn´t mentioned at all here. Since then, I´ve made a test install of SL, including Rosetta, and tried a few of my image handling sw. Since it might be of some interest in this thread as well, here´s a copy:
"Here are my findings (with reservations that there might be bugs or gotchas that I haven´t found yet):
Lightroom 2.5 runs perfectly, accessing my present library on its own drive.
Photoshop CS2 runs fine, and cooperates with Lightroom without a hitch.
Light Zone (latest version) runs fine, too.
Capture One (again, latest version) seems to run OK as well, but haven´t had time to test it much.
My Epson 3800 needed a driver download directly from Epson (wasn´t in Apple´s library), but seems to work OK."