A screen shot of the Picasa Web Albums home page taken on 10 April 2012.
Picasa is an image hosting service provided by Google. Picasa is also an image organising, editing and sharing application made by Google. As Panoramio, it's being killed in order to force users to use other services Google has invested more in.
Stable. Since March 2013, http://picasaweb.google.com redirects to Google Plus. Picasa Web Albums can still be accessed through https://picasaweb.google.com/lh/myphotos?noredirect=1, although its future is uncertain.
The "migration" was deceitfully sold as non-destructive, while stuff is actually killed in the process: see next section.
Creative Commons images
In fact, users and albums are often forced to "migrate" to Google Plus, without telling them that any Creative Commons marking will be irreversibly destroyed in the process. There's no way to mark Creative Commons images on Google Plus. There's also no way to search or browse Picasa Web by license, apparently (the feature used to exist in 2009).
Wayback has 320k URLs, so we should extract the photos which were already archived and are in CC. This might also provide a list of user IDs where further free images can be found. We'll then need a discovery to find all 21-digits user IDs who ever posted public Creative Commons images and dig their albums to find and download them.
Maybe Google would be interested in helping by releasing a free dataset as even Yahoo did (yahoolabs.tumblr.com/post/89783581601/one-hundred-million-creative-commons-flickr-images-for) and similar to the fotopedia collection.
Google is launching photos.google.com. It would be useful to find a timeline on when they expect a full launch, because usually that comes with forced migration of users and Picasa Web might be completely killed in the process.
The search redirects to plus.google.com and in general all discovery features seem to have been disabled, except the gallery used in the main page.
Accounts are in the form https://picasaweb.google.com/102652274152528116947/ , photos https://picasaweb.google.com/102652274152528116947/19012014?noredirect=1#5970659686273752802 , download link https://lh3.googleusercontent.com/-si1Onu-Rr2k/UtwLWcsXnuI/AAAAAAAAZpM/jHQ-9HCkGoM/d/%2525D0%2525B2%2525D1%252596%2525D1%252587%2525D0%2525B5%25252019%252520%2525287%252529.jpg
<a id="lhid_lic_text_cc" class="lhcl_license lhcl_license_greyTextColor lhcl_spriting_marginRight5" target="_blank" href="http://creativecommons.org/licenses/by/3.0/">Alcuni diritti riservati</a>