This is the notice displayed on Picasa Web Albums since joining Google+. It reads:
You've recently joined Google+. Note the following changes to Picasa Web Albums:
- Albums you've shared can in turn be tagged and shared by others.
- For new albums, anyone an album is shared with can see who else it is shared with.
- When you tag someone, they receive a notification and can see the photo and the related album.
I understand that sharing transparency and re-sharing are features that make Picasa albums more social, but I would really appreciate the option to turn them off. Sometimes I want to be less social. There's already re-sharing controls for individual posts on Google+. Why do you need to open up my albums too?