What is it?
Picasa is an image organizer and image viewer for organizing and editing digital photos, plus an integrated photo-sharing website. Native applications for Windows are available through Google Labs. For organizing photos, Picasa has file importing and tracking features, as well as tags, facial recognition, and collections for further sorting.
Description of picasa2.exe from Google
“Picasa can transfer, find, organize, edit, print, and share images, all with this easy-to-use product. Watch Picasa automatically organize all your pictures into elegant albums by date. Having all your photos in one place means no more time wasted searching for folders or files. The program works with JPEG, GIF, BMP, PSD, and movie files and is compatible with most digital cameras; it detects your USB driver and imports pictures into albums. Editing tools include cropping (standard or custom), removal of red-eye, and enhancing--even switching from color to black and white. Create slide shows set to your MP3s. Integration with Picasa's free Hello instant picture-sharing software lets you share hundreds of photos in seconds and chat in real time.”