The jump will be fueled by the continued growth of the installed base of Linux server operating systems into enterprise deployments.

"The data is not stunning to me," says Al Gillen, an analyst with IDC who co-authored the white paper. "I have been watching it evolve over the past several years. The biggest story is that the ecosystem is now real."

He says Linux spending surpassing the $20 billion mark is an important milestone. "But this does not put Microsoft on the ropes from a revenue perspective."

Gillen points out that the Linux business model differs substantially from the one that Microsoft has constructed. "So Linux is unlikely to ever get to the size of total revenue that the Microsoft market enjoys," he says.

Regardless, Linux is enjoying growth.

IDC's forecast for Linux server operating environments calls for 8.2% of compound annual growth from 2007 to 2012 for both new paid subscriptions and non-paid deployments.

IDC says the growth will be driven by paid subscriptions of commercial Linux distributions that are deployed on physical servers, virtual servers and other hardware types including redeployed server hardware and PCs and workstations that are used as servers.

But the future is not without potential roadblocks.

The white paper points out that Linux could face challenges from OpenSolaris if that alternative open source operating system begins to find favor on x86 platforms. In addition, the market dominating position of Windows also presents a challenge to long-term Linux success, especially as Microsoft competes to win Unix migrations.
But the changing nature of Linux deployments should give the open-source operating system a new avenue to seek prosperity.

The IDC study found that in addition to traditional infrastructure workloads handled by Linux server operating systems, such as DNS, DHCP and Web serving, that deployments for such applications as ERP and CRM are beginning to take hold.
For example, Novell and SAP extended a partnership in March that will have Novell supplying Linux-based platform, virtualization and identity support to SAP's small and mid-sized customers. 

Linux servers deployed for business and commercially oriented workloads, including business processing and decision support, will grow from 2001 through 2011 from 9% to 17.7%.

The IDC white paper showed that business processing deployments grew from 6.7% of Linux server operating system deployments in 2003 to 8.2% in 2007. Decision support workloads were up from 7.3% to 9.1% over the same time period.
IDC found that spending on software related to Linux server platforms is on a compounded annual grow rate of 35.7% from 2006 to 2011. 

Software on the Linux platform holds about 4% of the current overall market, which represents $10 billion of a $242 billion total. The Linux share is expected to grow to more than 9% by 2011, which will represent $31 billion in software revenue in a $330 billion market. The Linux Foundation Summit, which is an invite-only meeting, runs through Thursday with an agenda that focuses discussion around on-going development areas including desktop architecture, printing, virtualization,? mobile/embedded, power management, the Linux Standards Base OS and legal issues.