Is it possible to hide an app from App Store search results? We'd like to launch an iPhone app on an invitation-only basis to begin with. We'd like invited people to be able to find the app in the App Store via an email link, but not have other people be able to find it easily. Is this possible?
This is not possible with the App Store as apps released there are available for everyone.

You can use Apple's TestFlight beta distribution with the  TestFlight app to distribute a version of your app to invited people.