I don't even have an iSight camera, but was still able to manually enter the ISBN or UPC code. The app automatically switched context of which code you need to enter, depending on whether you were adding a book, CD, Movie (DVD or VHS), or video game!
There is a separate app that will export your iTunes to Delicious Library, called DeliciTunes.
This would be a great way to track your inventory for insurance reporting purposes. I could even see applying this to other kinds of items, such as Star Wars figures, that might still be MIB (Mint In Box) that you could scan the barcode and track! It would be nice if this app was configurable to add other types of collections, defaulting to UPC code, so you could track collections like this.
UPDATE: There's a cool easter egg! When you add a Star Wars title to your collection, after the app reads the title to you, a few seconds later, a deep whisper says "I am your father!". Nice touch! It would be cool if it also said "He's dead, Jim" or even better, "She 'canna take much more, Captain!" when you add Star Trek titles. :-)
UPDATE: Woohoo! I hooked up my Sony Handycam DCR-HC30 via firewire, and now I can use the barcode scanner! SWEET app!