I am not much of a KDE user but sometimes the features on offer from a KDE application are much more appealing than Gnome. One such application I recently came accross is DigiKam. DigiKam is a complete image editor, manager and one of the really good image organizers for Linux, besides Picasa.
With DigiKam, you can easily sort and search through images. DigiKam can organize your images based on tag, category, search result, date and time and a timeline. That makes it a complete photo manager.
DigiKam has the options of using ratings for individual images as well as to albums. The plugin support extends the use of DigiKam from the desktop to the web. There are numerous plugins to add support for Facebook ,Flickr, Google Earth and for creating web-albums. You also have the option to create easy web-galleries.
DigiKam also supports on the fly editing to images when they are being transferred to the computer from the Digicam.
The image editing features offered by DigiKam are red eye removal, color adjustment and various image effects. The newer version has support for GPS Locator, Metadata editor and iPod Photo Uploader.
The application is written in C++ and uses the QT frontend. It is also planning to use MySQL for the database which will allow the database to be shares and synchronized across a network. The development team behind DigiKam is quite responsive.
You can try DigiKam here: Get DigiKam [ approx. 13.5 MB ]
DigiKam is also available as a windows software: Get DigiKam for Windows