The total hardware cost for 24-node Beowulf cluster was $57,000 — as compared to most commercial supercomputers today, which cost between $10 million and $30 million.
—Parveen S. Thampi, “Linux Operating System: A Freeware and the Net War,” Computers Today, October 31, 1998
—Christina Dyrness, ”Beowulf looks to slay mainframe,“ The News and Observer, October 17, 2000
—Daniel Ridge, et al., “Beowulf: Harnessing the Power of Parallelism in a Pile-of-PCs,” Proceedings of the IEEE Aerospace, October 15, 1996
The most common explanation is the one given in the second citation. That sounds reasonable, but Beowulf clusters are designed to augment the work of supercomputers, not "slay" them entirely. A more tantalizing clue is found in the following cite:
—J. D. Biersdorfer, "The Secret Life of the Home Computer," The New York Times, June 8, 2000
It's likely the line that Dr. Sterling was talking about is the description of Beowulf by Hrothgar, the Danish king, where he says Beowulf "has thirty men's heft of grasp in the gripe of his hand" (translation by Francis B. Gummere):
Hrothgar answered, helmet of Scyldings: "I knew him of yore in his youthful days; his aged father was Ecgtheow named, to whom, at home, gave Hrethel the Geat his only daughter. Their offspring bold fares hither to seek the steadfast friend. And seamen, too, have said me this, who carried my gifts to the Geatish court, thither for thanks, he has thirty men's heft of grasp in the gripe of his hand, the bold-in-battle.Thanks to subscriber Frank Burns for pointing me in the right direction.
By the way, if you want to learn more about Beowulf clusters, see The Beowulf Project: