Rails has taken the right route and went for full disclosure unlike for example the WordPress team, who still believes in the flawed concept of security by obscurity. After a full assessment of the security vulnerability (details below) Rails team decided they needed yet another emergency patch to fully close the hole.

Here is the AdSense success formula from AdSense team. 1. A content-rich page = Highly-targeted ads 2. Highly-targeted ads + Interested users = Healthy clickthrough & conversion rates 3. Healthy clickthrough & conversion rates = Success! Source: Mike Gutner - AdSense Optimization Team