Picasa Web Albums 3 Beta features an entirely new and expanded collage maker. There’re six different collage “themes” ranging from a simple contact sheet to a “Picture Pile” that gives you complete freedom to arrange, resize and rotate pictures on a background of your choice. It's kind of like a virtual scrapbook.
If you're your composition skills aren't quite up to the task, press the “Scamble Collage” button and Picasa will rearrange the collage automatically. You can choose between various document sizes, including the most common photo, paper, and desktop screen sizes. This makes it easy to create postcards, CD covers, or even posters with just a few clicks.
Collages are saved like documents, you can go back to make changes or add new pictures to an existing collage. To do this, click the Edit Collage button at the top of the screen that appears when viewing a previously created collage. You can treat the collage like any other picture and apply fun effects like Soft Focus or Sepia, or maybe add a title using the new Text feature.
Note: all your collages are placed in a special Collages project album so that it's easy to find and edit all of your collages.
- Select a folder of pictures and press the Collage button
- Choose "Mosaic" in the collage theme drop list
- Choose "8.5 x 11: letter paper" in the Page Format drop list (or whatever size you want)
- Press "Shuffle Pictures" a few times
- To really add interest, explore the Grid Spacing slider and the Background Options
- Press "Create Collage"
Source:→ Google Photo Blog