Like any empire that reaches a critical mass, Microsoft is currently waging wars on many fronts. Two of its most troubling combatants are VMware, whose virtualisation software threatens its dominance of the corporate server, and Salesforce.com, whose on-demand CRM application has somewhat stolen the thunder from its Dynamics mid-range applications strategy.

In April, those two companies – arguably the most disruptive in the enterprise IT space during the past decade – announced a significant new partnership that sets the stage for what may well prove to be the critical battle in business software for years to come.

VMforce, a joint service that will be available later this year, will allow software developers to build applications using the Java programming language that run on virtual servers based in Salesforce.com’s data centres.

Were this the end of the story, VMforce would simply be a better-branded analogue of cloud computing services already available. But two critical characteristics make it unusual.

The first is the SpringSource Java application environment (the company behind which VMware acquired in 2009) that helps to simplify the development, execution and management of Java applications on virtualised systems. This forms the top layer of the VMforce ‘stack’. (It should be noted that it is already possible to use SpringSource on, for example, Amazon.com’s cloud platform).

The second characteristic is that VMforce developers will be able to use the component services of Salesforce.com’s application platform, Force.com.

Chief among these is the underlying data model, designed specifically for business applications. Others include Salesforce.com’s pre-built analytics functionality and new Twitter-like collaboration tool, Chatter. These services have previously only been available to those developers building on the Force.com platform itself, which uses its own proprietary (although Java-like) development language, APEX.

The combination of SpringSource and Force.com, the companies claim, will allow customers both to build new Java applications ‘in the cloud’ and, importantly, to port legacy Java applications across to the Salesforce.com platform.

As the number of neologisms contained with the last four paragraphs suggests, the VMforce service will appeal most immediately to business software developers at the cutting edge.

But according to Dr. Stefan Reid, senior analyst for Forrester Research, the launch of VMforce will push so-called ‘platform-as-a-service’ offerings – in which the building blocks of applications, not raw compute resources, are delivered over the web – into the mainstream.

For Reid the critical breakthrough is that VMforce can in theory support legacy applications, unlike Force.com whose proprietary language means only newly developed code can run on it. But while this is likely to open PaaS to a new audience, it will also “become a challenge for Salesforce.com’s go-to-market strategy and ecosystem,” Reid adds.

Above all, VMforce is “an attack” on Microsoft’s Azure cloud platform, Reid says. Microsoft has an upper hand over Salesforce.com, he says, in that Azure is based around .NET, which has a vast on-premise install base. But Force.com is a more complete hosted platform, he adds, and the addition of Java development thanks to VMware levels the playing field.

Many IT organisations might be today looking at the esoteric cloud computing services currently on offer and scratching their heads. But IT suppliers are working to make the cloud more accessible to companies further back than the cutting edge, and Salesforce.com and VMware’s joint project is a significant step towards making that happen.