The 27 Club isn't as fabulous as it used to be. Back in the 60ties, the founding members of the club were all bona fide superstars: Janis Joplin, Jimi Hendix, Jim Morisson and Brian Jones. Nowadays any musician dead at 27 is admitted by the insatiable wikipedia curators.
Amy Winehouse is no Janis Joplin. Kurt Cobain wasn't a bad vocalist, but he isn't in the same league as Jim or Jimi. Robert Johnson, Jacob Miller and Pigpen of the Grateful Dead also died at 27 but hey, you gotta draw the line somewhere. The real 27 Club has four members. No more no less.