This is a feature we should have had months and months ago, but it got left behind, alas - partly I had to learn how to do it. Now, after a frenzy of programming, I'm ready to launch it and was hoping for a few testers to give it a shot.
Right now you will be able to import library files from LibraryThing, Shelfari and GoodReads to populate your bookshelf. If anyone would like to help test it out, you can do so by going to http://www.cookbooker.com/import.php and following the directions. In my own testing, it has worked just fine on files from all three websites, but there's nothing like getting other people to test something out to find the flaws.
If you do use this, please email me using the 'contact us' link at the bottom of any page, or reply to this discussion thread, to let me know how it went for you. Right now it just pulls in the ISBNs from your file and then connects them to Cookbooker titles, allowing you to preview them before adding them to your bookshelf (and also allowing you to add new books to the site). If there's a demand for it, I can also look into grabbing ratings and reviews from the websites; this is a little more complicated, but should be doable.
If you use another website or a software program to organize your library, let me know and I should be able to add it to the import list - I'll need a copy of your exported file to examine it first.