Zopenewbies reports that spammers have discovered a hole in MT which they have used on MT weblogs to send chunks of spam to AOL over the last few weeks. The hole relates to mt-send-entry.cgi, and they recommend disabling it or running one of the patches listed on the site.
UPDATE SixApart has responded by releasing a new version of 2.6.4 available here, and also has provided information on how to deal with the problem
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