The latest Chromium build adds an option to encrypt all data in the browser sync.

http://2.bp.blogspot.com/-LtkKzYiJwa8/TdxztfPSJgI/AAAAAAAAAeY/9CmUyisAMVI/s1600/google-chrome-sync-encryption.jpg

http://www.browserscene.com/2011/05/google-chrome-gets-sync-data-encryption.html

Pointing to
http://src.chromium.org/viewvc/chrome/trunk/src/chrome/common/chrome_switches.cc?revision=86510&view=markup