The other high-priority fix closes the door to a potential attack that could use malicious XML on a web page to crash a Chrome tab process and run arbitrary code. The code would be run within Google's sandbox. See CVE-2009-2414 and CVE-2009-2416 for more on the fixed bugs.
Finally, with this new Chrome update the browser will no longer connect to "HTTPS (SSL) sites whose certificates are signed using MD2 or MD4 hashing algorithms".
For more details on the new 220.127.116.11 update, see Google's blogspot post.