"Nasa officials rejected applications from Chinese nationals who hoped to attend the meeting at the agency's Ames research centre in California next month citing a law, passed in March, which prohibits anyone from China setting foot in a Nasa building. The law is part of a broad and aggressive move initiated by congressman Frank Wolf, chair of the House appropriations committee, which has jurisdiction over Nasa. It aims to restrict the foreign nationals' access to Nasa facilities, ostensibly to counter espionage."
Keith's note: Some of the scientists who are quoted in this article with complaints about NASA have apparently been living under a rock for the past several years. Newsflash: It is utterly illegal for NASA to allow Chinese participation - in any way. Complaining about NASA's decision is simply ill-informed. Where were all these people when this law was being formulated - or when hearings were held on it? Dumping on NASA or boycotting this meeting is pointless - only Kepler will suffer. If a change in the law is what is needed then these people need to talk to Congress about that - starting with Rep Wolf.
Check H.R. 1473 (112th): Department of Defense and Full-Year Continuing Appropriations Act, 2011, Sec. 1340. (a) to see the sort of prohibitive language has been in place for several years. NASA's hands are tied.