Several users are complaining that they had a problem with CUPS resulting a black paper when printing. Today, a new update has been released on 13.1 and -Current to merge an upstream patch which hopefully be able to fix the problem.
Also, i noticed Firefox 3.6.6 has been released today. I wonder, since few days ago they released 3.6.4 and i didn't see any 3.6.5 release but they bumped into 3.6.6. The only change is the increment of amount of time that plugins are allowed to be non-responsive before being terminated.
I don't think it will be released as a security update, but rather a minor update.