A bit late in the day, but this might help:
Picasa2 does run under OSX provided you install Darwine first. I have it running so and prefer it to iPhoto as it doesn't take up disk space with copies of pics - in another, proprietary, format - that I have already. Its UI is pure Windows, alas, but that's OK as it's running in Windows-alike Wine anyway.
I am currently trying to find out in another thread how to have OSX open a Wine prog when it detects the camera being plugged in. You might need to know this soon!