Workhabit customer YourSphere was featured recently in a case study on Drupal.org.
The case study shows how YourSphere is building a secure, safe, and private social network just for teens. They describe how things are built, going into some good detail on the profiles and how the developers made it easy for non-expert admins to add content.
There's a particularly nice mention of WorkHabit's scalable Drupal hosting platform, Elastic 2.
Social networking sites are especially hard to scale on the database tier having fewer caching opportunities. For example, with Yoursphere's particular application the team expects to see a couple spikes in traffic each afternoon and almost no traffic at night. The ideal infrastructure would automatically scale the web and database tiers based on actual current load--provisioning an extra dozen boxes for just one hour each day to handle a traffic spike, and then offloading the extra servers when no longer needed. This was achieved by partnering with WorkHabit to prototype their ground breaking Elastic2 cloud-based, auto-scaling Drupal platform. With the automatic scaling promise of cloud computing fully realized, Yoursphere can scale to billions of pageviews or more, allowing us to focus on building a really fun product rather than babysitting servers.