At the Black Hat Europe 2010 conference, taking place in 
Barcelona, Spain, from April the 12-th to April the 15-th,
Haifei Li and Guillaume Lovet will give a presentation
named "Adobe Reader’s Custom Memory Management: A Heap of Trouble“:

  [1] http://www.blackhat.com/html/bh-eu-10/bh-eu-10-briefings.html#Li

focusing on the subject of custom heap management system,
present in the Adobe Reader.

As part of their presentation, they will publish a working 
exploit for "a PDF zero-day vulnerability they discovered
recently in the latest Adobe Reader 9.3.1 (where Data Execution
Prevention is enabled by default), as a demonstration of
their research."
 
  [2] http://www.youtube.com/watch?v=9EVHtY1-0q8
  [3] http://blog.fortinet.com/the-upcoming-blackhat-europe-2010-presentation/

As stated in [3]:

"Please note that the vulnerability details are currently being
protected by our Responsible Disclosure Policy. We are working
actively with the Adobe Product Security Incident Response Team
to arrange an appropriate timing to disclose the full details."

The Red Hat Security Response Team is aware and monitoring progress
on this flaw, cooperating with Adobe Product Security Incident
Response Team and once further information is available regarding
this threat, will immediately react to ensure it will be addressed
in a timely manner.