The new SMB2 stack has a lovely exploit in it, that's very close to the old 'Ping of Death'; and lets you send a single packet to bluescreen a machine running (fully patched) Windows 7, and was later confirmed to affect Server 2008 and Vista as well. It's very close to a RCE exploit as well, there's the potential for it there, but we've yet to see a working PoC...
http://isc.sans.org/diary.html?storyid=7093
