The Digital Public Library of America launch event is open to all and there is no charge to register/attend.
From a DPLA Announcement:
Convened by the DPLA Secretariat at the Berkman Center for Internet & Society and co-hosted by the Boston Public Library, the two-day DPLA Launch will include a brief working day on Thursday, April 18th, followed by a formal reception featuring presentations and a series of interactive exhibits showcasing content from our many partners, including the Digital Hubs and Europeana. On Friday, April 19th, the DPLA will convene a focused half-day plenary meeting highlighting the DPLA’s progress and potential.
We invite all those interested from the general public, the educational community, public and research libraries, cultural organizations, state and local government, the creative community, publishers, and private industry to join us at the launch.