Picasa 3.8 doesn't add too many features, but there are at least two reasons for updating to the latest version: Face Movie and batch upload to Picasa Web Albums.
Face Movie is a movie presentation centered around one person. "As the photos transition from one to another the subject's face stays aligned in one focus area, creating a unique viewing experience," explains Picasa's blog. Just select one of your contacts from Picasa's sidebar and click on the create Face Movie.
Picasa 3.8 makes it easy to upload multiple albums to Picasa Web and change the settings for the existing albums. You can delete multiple albums, change their visibility, save space by changing photo size or disable syncing. Go to the Tools menu and click on Batch Upload to access this feature.
Google's photo manager also added a surprising feature: integration with Picnik, the online photo editor acquired by Google this year. Why would you use a slow and limited online service to edit photos stored on your computer, when you can use Picasa's image editing options? Picasa's help center explains: "Use Picnik's exclusive editing features to apply effects, stickers, and frames to your photo. You can also crop, and adjust the colors of your photos right in your browser. When you click on Edit in Picnik, your photo will be transferred online. Apply the desired effects then click Save to Picasa. You'll have to option to replace your original photo or create a new copy on your computer."
In Windows, Picasa uses an Internet Explorer object to display Picnik's Flash site. I had to click on two Internet Explorer script error messages before uploading a photo to Picnik.
Unfortunately, most Picnik stickers and touch-ups require upgrading to Picnik Premium. Why would Google charge users $25 a year for this service? I remember that Google made Blogger Pro, Picasa, Keyhole's Earth Viewer (now Google Earth), Urchin, Sketchup, FeedBurner Pro/MyBrand free after acquiring the products.