Icarus. I didn't like any of the other options for uploading files to Picasa Web so I wrote my own. It's more an educational experiment for me with the Vala programming language.
This provides a very weak library to post images and get some album information. It also includes a command-line programme providing an interface to this library's features.
It hasn't got the best security as it requires you to leave your Picasa Web password in plaintext on your hard drive in a configuration file.
I mostly use it in conjuction with Nautilus Actions to have a Upload to Picasa Web menu entry for images and videos that uploads it to Picasa Web's drop box.
Good or bad, you do not need to have any Google libraries installed because this handles the communication itself.