In case you haven't noticed, more free open source image viewers are able to edit metadata lately. With this release gThumb, a GNOME image viewer, joins that very club.
Changes in this new version are:
- refactoring of source code for better maintainability and extendability;
- importing and exporting from/to Picasa WebAlbums, Facebook, PhotoBucket, Flickr;
- GNOME keyring is used for storing passwords;
- IPTC/XMP metadata fields can be edited now;
- audio and video files can be played finally (think about all the DSLRs and point-and-shoots that can record video files and audio comments);
- improved filtering and sorting of image files;
- more keyboard shortcuts;
- other, less significant changes;
You can download source code.