In March, SCO Group filed a lawsuit against IBM charging unfair competition and breach of contract. IBM's promotion of Linux, SCO said, could destroy the value of Unix on Intel-based computers. It was during technical research for this lawsuit, McBride says, that SCO discovered its Unix code within the Linux kernel. Now, SCO is threatening to revoke IBM's Unix license, which it uses to sell its AIX operating system, June 13 if no resolution is reached. A spokeswoman for IBM says the company intends to defend itself vigorously and believes its Unix license is "perpetual and irrevocable."

Meanwhile, SCO's actions have created a backlash among Linux programmers. May 2, SCO's Web site was disabled for several hours by a distributed denial-of-service attack, which flooded the site with bogus traffic.

In any case, SCO's tactics look to some like an act of desperation. "SCO seems willing to play as hardball and as dirty as they can," says Gordon Haff, an analyst with IT research firm Illuminata. "My view is, they want to be bought. I don't see how they can continue in this business long term after this."