Enterprise cloud provider Tier 3 announced today it has built and open-sourced “Iron Foundry,” a .NET environment for CloudFoundry, VMware’s fast developing platform as  a service (PaaS).

The move exemplifies Tier 3’s flexibility in developing enterprise cloud environments and Cloud Foundry’s ability to go beyond Linux as a development platform.

Further it validates CloudFoundry’s place as a major service and the importance of PaaS in the overall market.

All together, it gives some early glimpses into the winners and losers in the platform market. In particular it raises questions about Microsoft, which is not actively pursuing a private cloud strategy and the growth of polyglot platforms such as CloudFoundry and Heroku.

Krishnan Subrmanian made the point to me last night that it may cost Microsoft some business. He said many enterprises users (mostly Windows shops) want Azure private cloud and Microsoft is not giving them what they need. Those shops will now look at CloudFoundry as an option and give Tier 3 a market opportunity to to build private clouds for Microsoft customers.

Tier 3 CTO Jared Wray said Java and .Net made the point in an interview yesterday that the two most common programmer languages in the enterprise. CloudFoundry supports Java. With .Net, Tier 3 can use the platform for internal use and eventually offer it as a service to customers.

Developers can access IronFoundry.org for both a Windows version of Cloud Foundry Explorer as well as a Visual Studio Plugin for Cloud Foundry. Tier 3 will also make the core code available on GitHub under an Apache 2.0 license.

“Making .NET compatible with the ecosystem was hard to do,” Wray said. “CloudFoundry did a great job of making a modular architecture.”

CloudFoundry’s openness and its ability to serve as a private cloud environment gives Tier 3 a way to compete on Azure’s turf.

It also signals a shift in the market. Enterprise customers are building private clouds and they need to have platforms that abstracts the infrastructure.

The question: Is Azure strategy starting to degrade and what does that mean for the market?