http://googlephotos.blogspot.com/2010/02/search-by-camera.html

Search by camera

 

In the past year, we've added several advanced search options for finding public photos in Picasa Web Albums. To help you find the right photo, you can filter your search by aspect ratio, size, photos vs. videos, photos with faces, and more. We're now happy to add one more dimension: the ability to search by camera. Searching by camera allows you to sample the quality of photos taken with a particular brand of camera or a specific model, and could help you make a decision between buying a Nikon D90 or a Canon EOS 50D.

To search by camera, first do a search in Picasa Web Albums. Click the 'Show Options' button, click 'Camera Models...' and then either choose your preferred make or type in a specific model.