Yahoo have announced that Delicious has been bought by a new company called AVOS, owned by the founders of YouTube. They will take over Delicious in July 2011, maintaining the service as it is (same web address, same look and feel) and developing it further from there. In order to continue using Delicious after July 2011, you must log in and accept AVOS's terms of service and privacy policy, which will allow them to take over your bookmarks with the service as a whole.

More information about the transition:
Delicious blog
FAQs on Delicious
AVOS press release