Google+ and Picasa Web Albums: Who can see the people I've shared with?
When you share photos and videos on Google+, the people that see your post or album will also be able to see who you've shared a post with and see who you've shared an album with. Albums created before signing up for Google+ are an exception. To be clear:
For albums created before signing up for Google+
No one but the owner of the photos can see who the post (and photos) are shared with.
For albums created after signing up for Google+
- Anyone that can see the post in Google+ can also see who the post (and photos) are shared with.