DotNetNuke the largest Web content platform built on the .NET Framework boasts over 6 million downloads since it's release in 2009 sa release the Enterprise Edition. It's a fully opened to custom apps. Version 5.5 is an earnest attempt to move beyond small business and into the enterprise arena.
The DotNetNuke Enterprise edition offers staging capabilities allowing developers to create test environments before moving to production. It also compares the production and liver servers to help identify missing components. It also features more robust support, offering unlimited second level support with architects and engineers, access to the online knowledge base and eltie support for enterprise level customers.