The dark secret about duckduckgo.com
ted-is-a-nerd.tumblr.com
ted-is-a-nerd.tumblr.com
if you are insinuating that duckduckgo is actually operated by google, that is a different story. But just hosting an app on their services doesn't seem to cause an issue to me.
If the insinuation is that google is in fact collecting private information via duckduckgo because it is run on appengine, I'd like to see some proof of that.
Google Apps: http://www.google.com/apps/intl/en/business/index.html
Google App Engine: http://code.google.com/appengine/
It's actually a pretty good idea to sign your domain up for the Google Apps free plan regardless of your project--it saves you the trouble of having to configure a mail server.