Digital Scrapbooking is the creation of scrapbook pages or albums on a computer rather than by hand (though you can create hybrid pages that use both). Based very much on its real-world forebear, digiscrapping uses a combination of papers, photos and other elements to produce attractive pages that document a moment, remember a person or express an emotion.
Digital Scrapbooking On Linux
There isn't the plethora of scrapbooking-specific software for Linux that you find on Windows but there are plenty of great image/graphics programs available and at least one Windows scrapbooking app works on Linux using Wine.
The GIMP will do pretty much everything that you'll need with photos and for creating the pages themselves, certainly anything that PhotoShop Elements can do. For simpler tasks (cropping photos, etc) Pinta is a quick and easy alternative. If you're looking for a scrapbook-specific program, the only one I've found that runs on Linux is Scrapbook Max. This installs and runs very well using Wine 1.3 (tested up to 1.3.25).
The GIMP opens PSD files and can use PS brushes, though not PS actions. Other file formats shouldn't be a problem; the standards in digital scrapbooking kits are JPG (papers) and PNG (elements).
Digital Scrapbook Kits
There are some amazing scrapbook kits available for immediate download from any number of stores and membership sites online. Personal favourites include Digital Crea, Deviant Scrap and Creative Victorian for Steampunk bits. If you're looking for something specific, Google is the way to go.