It's hard to gauge the full breadth of open-source software. In most cases, users are free to download and use the software without contacting the company that made it. Only a fraction of those wind up signing a contract.
But there's ample evidence of open source's growing clout.
Just a few years ago, it was hard to find Linux versions for some of the most popular software applications for business.
Today, executives say more than 750 major business applications run on Linux.
"It's a rare occasion when someone important in the (software) industry decides not to support Linux," said Oracle President Charles Phillips, in a speech at the recent LinuxWorld trade show in San Francisco.
Another sign of open-source growth: Every major hardware vendor sells Linux systems alongside those running Unix and Microsoft Windows.
According to International Data Corp., server vendors sold $4.2 billion worth of hardware running Linux in 2004.
That's small compared to the $18.9 billion worth running Windows and the $17.6 billion running on the various versions of Unix. But for Linux, the total reflected a 44.2% jump, vs. 14.6% for Windows and a 1% drop for Unix.
The Next Wave
Beyond Linux, a new wave of open-source software is gaining traction.
More server makers are reselling open-source software in areas such as databases and middleware. Most run on Linux. Some run on Windows and Unix systems.
HP recently deepened its ties with open-source firms MySQL and JBoss. Customers demanded it, HP officials say.
MySQL CEO Marten Mickos says sales have doubled every year since the database maker began 10 years ago, reaching $20 million last year. The software helps run some of the best-known Web sites, including Google (GOOG) and Yahoo. (YHOO)
Privately held JBoss doesn't reveal sales. But it has signed several high-profile deals in recent months and is supported by every major hardware vendor.
According to a recent online survey, JBoss is the second-most used application server behind IBM, beating out several commercial rivals.
Meanwhile, 10,000 companies in 50 countries use open-source JasperSoft, say its creators. The San Francisco-based firm raised $8 million in venture capital this summer.
Name a software program worth paying for, and you'll find at least one open-source counterpart that promises similar features for a lot less money.
"You can build an entire ecosystem out of Linux and open source," said IDC analyst Jean Bozman.
VCs Vote With Wallets
Another measure of open source's rise is the flow of investment money. Research firm VentureOne says open-source firms garnered $149 million in funding last year.