Amazon is ending its data partnership with Goodreads, effective January 30, which means that Goodreads might lose part of its database as it has to cease using amazon's data. More details here:
http://www.goodreads.com/topic/show/780951-faqs-amazon-is-going-away-as-a-data-source They have new sources of data for most of the books, and volunteers are working on "rescuing" many more. However, if you have a lot of books on your shelves that are less than common - especially books in languages other than English - now is a good time to export your books to a csv file, so that if you lose any of them you'll know what to add again later.
To export yourt books use the link in the top right corner of this page:
http://www.goodreads.com/review/import