Turns out NBC isn't beneath a little petty theft itself. A month after Peacock brass accused Fox of stealing its boxing-show concept, NBC has burglarized Fox's talent pool and made off with Arrested Development scene-stealer Will Arnett — albeit temporarily. The actor, who plays misfit magician Gob on Fox's acclaimed satire, will appear on Will & Grace's Sept. 23 episode as Jack's dance foe. "They're vying for a job as [special guest star] Janet Jackson's backup dancer," explains exec producer Alex Herschlag. So how does Fox feel about sharing Arnett with crosstown rival NBC? "We're thrilled that Will's on two Emmy-nominated shows now," insists a network rep. In the meantime, don't be surprised to see Rosario cleaning toilets on North Shore during sweeps.