One of the best descriptions was given in the 2009 JavaOne Conference PDF:
"The Java Champions community was started by Sun at the 2005 JavaOne conference to recognize key influencers in the Java community. Java Champions are influential Rock Star presenters and Java technology educators, authors, and consultants; Java platform event organizers; and others within the Java technology ecosystem. For the third consecutive year, Java Champions have contributed to the JavaOne conference process as technical reviewers for paper submissions, have been recognized for their achievements, and have shared their thoughts about the state of the Java platform at their BOF sessions." From javaone-2009.pdf
Note: This list is maintained by the Java Champions themselves.