For those who didn't notice it.  On Wed, Cisco posted a bulletin about a potential memory exhaustion (denial of service) vulnerability with PIX and ASA (but not FWSM) devices running software version 7.2 configured as DHCP relays.  Updating to 7.2(2.15)  fixes the issue.

References:
http://www.kb.cert.org/vuls/id/530057
http://www.cisco.com/warp/public/707/cisco-sr-20070502-pix.shtml
http://nvd.nist.gov/nvd.cfm?cvename=CVE-2007-2461