Jenna from DanRadcliffe.com (a trustworthy source) says Daniel Radcliffe and Emma Watson will NOT be appearing in Mexico at a John Williams concert, as previously reported:
Earlier this week it was reported that Emma and Dan would be appearing as guests for the John Williams concert at the Silvestre Revueltas Room, in the Cultural Centre Ollin Yoliztli, on December 19th, 20th, and 21st.
I am sorry to disappoint all of the Mexican fans out there, but after consulting with official sources at the studio, we have received word that neither Dan or Emma will be in attendance as they have school and filming commitments at that time.
Editor's note: Sorry for getting everyone excited over nothing. It wouldn't have been reported as "fact" if the Associated Press and other news outlets in Mexico hadn't "confirmed" it. In fact, I held out posting the news upon first hearing it, until I saw it come across the wires. Even CNN ran it, so mistakes were made all around, it would seem.