Well, really exist a few information about this.
But i find a simple solution using normal http requests. Here's the link:
http://rcs34-android.blogspot.com/2012/09/connect-to-picasa-album-from-android.html
and check too the Picasa Developer References.
If want to upload a picture is simple too. Use something like multipart and in a few lines will be work.
Also can check the code in gdata, to get a few knowladge about the structure and how you can implement it.
https://code.google.com/p/gdata-java-client/wiki/Dependencies
Thanks to RCS-34 for a simple solution.