Psst! Think you know everything about the residents of Wisteria Lane? Well, you might not have realized it, but Melrose Place alumnus Doug Savant isn't an official series regular on Desperate Housewives.

That seems odd, considering the 41-year-old thesp did the talking when the show's stars picked up their SAG Award for best ensemble cast this month.

Here's the sitch: This season, each time Lynette's husband Tom shows up on screen, Savant is listed as a guest star — he's the only partner of the

Housewives to be so credited. Yet he's not on the permanent cast roster. What gives? "I guess it's because I'm out of town all the time," he says with a laugh. "When a show starts out, nobody knows whether it's going to be a hit, and everybody's trying to save money. [Creator] Marc Cherry told me this was one of the ways the show could get done without having too enormous of a cast."

But that's going to change next year, has learned. Savant is being minted as a regular cast member starting next season. Hey, it's only fair. After all, Tom's been home enough lately to hire a curvaceous nanny — whom he fired after eyeballing her in the buff — then get locked out of his own house, along with his adulterous father. (Tom's papa was played by Ryan O'Neal, which certainly says something about the nighttime sudser's appreciation of Savant's character.) Promises Savant: "I'm here for the long haul."