I believe that my images from Google+ and from Picasa web album can both be found in either application. I can search for an album name or an image caption or a file name in Picasa web album. Can I do the same from Google+?
The search in Google+ currently doesn't allow you to search through photo information. However, Google's Search Plus your World can provide the results you're looking for directly in Google's regular search. Here's some documentation on personalized search results
From the regular Google search box photos will surface in the results (in the Images section) if you are signed into Google. Caption information is also searchable.
Edit: Another help center article on personal search results