Also, first official English website site.
Danny Choo has just announced through twitter that Hatsune Miku will be performing in concert at Anime Expo 2011. The official website is now up at http://mikufes.com/ which runs on the Mirai Gaia blogging platform and is the first official website for Hatsune Miku in English. The concert will be held in the Nokia Theater on July 2nd and is based on the "Miku's Day Thanksgiving" event, but with improvements. The announcement page adds that three other Vocaloids, Len, Rin, and Luka will be performing as well. Anime Expo will take place July 1st-4th at the Los Angeles Convention Center.
Image ©Sega ©Crypton Future Media
Update: Added additional details