Comic-Con took place last week, and featured a well attended tribute panel which included Margaret Atwood, Sam Weller, Marc Scott Zicree and others. There are plenty of accounts of this panel on the web, such as this one.
Zicree talks more about Bradbury in this BBC radio interview.
Fans in Pittsburgh staged their own tribute by reading Bradbury stories.
Other tributes inevitably come wrapped up in reviews of the new tribute volume Shadow Show.
Gloria McMillan of Arizona University has put out a call for papers inviting scholars to contribute to a proposed book with the working title The Tucson Bradbury Chronicles: Mars is The West. This essay volume will take as its starting point the fact that the young Ray Bradbury lived for a while in Arizona, but will explore Bradbury's engagement with the western US in broad terms. Such academic volumes are often a long time in development, so it may be some time before anything comes of this, but I will post more information when it becomes available.