Google has released Picasa 3.0 Beta for Linux with improved Linux desktop integration. For instance, it now uses your preferred file manager, and you can use your preferred email program to send photos directly from Picasa. Picasa even integrates with the camera detection features in Gnome and KDE, so your desktop environment will ask you to launch Picasa when you plug in your camera. Native Firefox integration also makes it easy to download entire albums from Picasa Web Albums with just a click.
All important features of Windows release are present in this release: Along with faster performance, Picasa 3 for Linux introduces new features like automatic web sync, a greatly-improved collage tool, a powerful retouching tool, and an intuitive text tool that's both fun and useful.
You can also use the Google Linux Software Repository to install and stay up-to-date with all of Google's Linux software.