Have been using Picasa for over two years now. I first spotted a professional photographer used it to do some minor touch-up right after my event, and gave me a thumbs-up when I asked what program it is. It is indeed useful since PR people like me will always ask for photos right after the function is over (or they will not be allowed to leave the door, haha). I tried it out and basically got latched onto this simple yet great program ever since.
Just got upgraded to Picasa 3.0 and glad to find that a number of new features are added. I like the neat interface with improved editing and sharing options. The share option can help users to upload photos online and email links of your Picasa web album to friends. The photo organizer also automatically detects faces and corrects the red eye in the photos. The latest version also adds in a movie maker function which allows you to make some basic video with stills. However, avoid importing too many images to Picasa at one time because it eats a lot of memory and would bring a clear performance impact.