A double free vulnerability exists in perl 5.8.8. A result of a UTF8 crafted regular expression, this vulnerability could cause a denial of service on certain operating systems. This has not been fixed as of the time of this writing.
A curious vulnerability has been announced for Trillian 3.1 where a specially formed nickname can cause a buffer overflow in Windows. Very few details are available at this time, and an exploit hasn’t been released, but I wouldn’t expect it to be long before we see a real PoC.