I didn't see this posted anywhere, but I attended the Chicago Grammy Viewing Party where we were given the Grammy program booklets. An excerpt:

"The Grammy Hall of Fame was created in 1973 to honor recordings of lasting significance that were issued prior to the 1958 inception of the Grammy awards. The Hall is now open to any recording that has been in release for at least 25 years. New submissions are voted on annually by a special member committee of experts and historians drawn from all branches of the recroding arts. Their choices are subject to final approval by the Trustees of the Recording Academy. The Grammy Hall of fame is unique in that it is open to all generes of music--popular as well as specialized forms"

Prince made the Hall of Fame this year for the album 1999.

Well-deserved, congratulations!

There's already a thread on this http://prince.org/msg/7/260824