This workshop looks like it would have been interesting; held today in Boston. For now, you'll have trouble getting the papers unless you're a subscriber, but you can browse the agenda ...

You'll find more security vulnerability research from Google.

You'll also find "Billing Attacks on SIP-Based VoIP Systems", by a team from George Mason, including Xuxian Jiang and Xinyuan Wang.

First USENIX Workshop on Offensive Technologies (WOOT '07)