A few new rules in this release, here's the highlights:

MySQL Denial of Service (CVE-2009-0819):
A programming error in MySQL Server may allow a remote attacker to cause a Denial of Service (DoS) against a vulnerable machine.

Mozilla Firefox XML Buffer Overflow:
A programming error in Mozilla Firefox may allow a remote attacker to execute code on a victim machine. The error is exposed when the application attempts to process a specially crafted XML file.

As always, details are available here: http://www.snort.org/vrt/advisories/vrt-rules-2009-03-31.html