What is this all about? Well, it stems from the findings of a 1990s US federal case which found Microsoft had been acting as a monopoly by forcing computer firms to take its software. This payout to IBM, however, is specifically to settle discriminatory pricing and overcharging allegations made by IBM.
"With these antitrust issues behind us, both Microsoft and IBM can move ahead, at times cooperatively and at times competitively, to bring the best products and services to customers," said Brad Smith, Microsoft's general counsel and senior vice president.
Now that Sun and IBM have had their pound of flesh from Microsoft, who is next? Well, funnily enough this comes on the eve of breaking news that Go.Corp (which once looked as though it might capture the market for tablet style operating systems) has filed papers in the US against Microsoft, alleging anti-competitive behaviour.
The allegations detail a standard modus operandi for companies suing Microsoft. He says that Microsoft engineers came to visit Go and were shown the company's technology. Later very similar technology appeared in the Windows Tablet Edition.