Two popular past guest stars will revisit their NBC homes-away-from-home during May sweeps. Jean Smart reprises her Emmy-winning role on Frasier as bitter ex-prom queen Lorna Lindley for a few episodes. In the first, titled "Semi-Decent Proposal," Frasier escorts Lorna to her surprise birthday party. Also, SNL alum Molly Shannon pops up for an installment of Will &#038 Grace as "loon-a-chick" Val, who stalks Jack (Sean Hayes) like an obsessed fan after he relaunches his forever-flopping cabaret show.