From the announcement:
Bowker, a leading global provider of bibliographic information solutions and services, has reached an agreement with Google to provision and facilitate the assignment of ISBN numbers to Google Editions, Google's digital book offering launching later in 2010. The agreement sets an important publishing industry precedent, helping to ensure a standards-driven framework for the identification of digital and print-on-demand book products made available and sold through Google Books. Bowker operates the U.S. ISBN Agency.Under the terms of the agreement, Google will assign ISBN numbers to Google Editions in cases when book publishers have not assigned their own unique ISBNs to works they intend to make available for sale. Both Google and Bowker will encourage publishers to retain primary responsibility for assigning their own ISBNs to their respective Google Editions and including these records as part of the catalog data they distribute to their trading partners.