Spencer Ackerman sees the use of the Stuxnet worm on Iran's nuclear capabilities (by what appears to be a joint US-Israel collaboration) as a milestone for cyber warfare:
With Stuxnet, there’s no broader conventional assault, but an adversary’s most important military asset gets compromised. The mission of an aerial bombardment of Iran would be to set Iran’s nuclear program back; to at least some degree, Stuxnet has done precisely that. Only Stuxnet didn’t kill anyone, and it didn’t set off the destabilizing effect in the region that a bombing campaign was likely to reap.
In other words, Stuxnet may represent the so-called “high end” of cyberwarfare: a stealthy, stand-alone capability to knock an opponent’s Queen off the board before more traditional military hostilities can kick in.