XSRF vulnerability.  It is available at
http://github.com/downloads/facebook/tornado/tornado-1.1.1.tar.gz

This is a backwards-incompatible change.  Applications that previously
relied on a blanket exception for XMLHTTPRequest may need to be modified
to explicitly include the XSRF token when making ajax requests.

The tornado chat demo application demonstrates one way of adding this
token (specifically the function postJSON in demos/chat/static/chat.js).

More information about this change and its justification can be found at
http://www.djangoproject.com/weblog/2011/feb/08/security/
http://weblog.rubyonrails.org/2011/2/8/csrf-protection-bypass-in-ruby-on-rails