Nothing is official quite yet—the paper quotes an anonymous source with "knowledge of the negotiations." If the deal goes through, though, it would combine not just Sun's and IBM's meaty server businesses, but also give IBM control over Solaris, Java, and MySQL. Unsurprisingly, the NYT says the move "could prompt an antitrust challenge."
Judging by recent Gartner numbers, the two companies would have accounted for 17.3% of worldwide server shipments and 43% of global server revenue last quarter.
Sun has reportedly been seeking a buyer since late last year, and company officials have been meeting with "representatives of other technology companies." The New York Times points out that IBM may seem like an unlikely candidate, since it has been shifting its focus from hardware sales to services in recent years. However, a merger would "bring together two technology companies that have continued to invest heavily in research and development, when many of their corporate peers have cut back to shield profits."