I believe that FogBugz used this approach, back in the day (with a SQL Server backend). The reasoning was that customers data couldn't ever leak into each othe

I believe that FogBugz used this approach, back in the day (with a SQL Server backend). The reasoning was that customers data couldn't ever leak into each other, and moving a customer to a different server was easier. I vaguely recall Joel Spolsky speaking or writing about it.