Google has a preview release of Picasa 2.7 for Linux. The previous version launched last year didn’t include the features from Picasa 2.5+ for Windows (like the Picasa Web integration), so this is a good opportunity to add these features to Linux. Here’s what is new in Picasa 2.7 for Linux:

• Upload to Picasa Web Albums - Use the new "Web Album" button to post your best photos online to share with friends and family.
• Save edits to disk - Save edits, undo saves, and revert to the original file with ease. We’ve got batch saving too! Picasa will even match the jpeg quality of the original. Right-click on your saved files to try the new "locate original" feature.
• Folder hierarchy views - Browse through folders Explorer-style. Use the button at the top of your Albums List to try them out.
• Improvements to Import - Import into an existing folder. (…) We’ve made importing photos from your camera faster too.
• Better RAW support - Now you can work with RAW files from the Canon 30D, the Nikon D200, Adobe DNG files, and more.
• Many other enhancements - Larger thumbnails, better caption editing, ability to configure the row of buttons, special "Starred Photos" album, search by ISO and focal length.

The release still doesn’t support videos, full-screen slideshows and it’s still using WINE.
More about Picasa for Linux at Google Groups.