Hi,
yes I have a few clients that have gone AWOL in Google. They all have different ages, numbers of backlinks, different markets, but their sites have gone mostly supplemental in Google in the last few weeks.
The one thing I am seeing in common is that the sites in trouble don't have a 301 redirect from the
http://example.com to the
http://www.example.com.
Cheers,
Paz.