I think this is hideously overblown. Kate is a model and works in the fashion/entertainement industry. Yes, cocaine use is fairly rampant in those industries. Yes she is also going out with a complete muppet dickhead who sometimes glorifies drug use and should be put out of everyone else's misery (can you tell I'm not a Pete Doherty fan? :p). But I do feel the media circus surrounding her 'possible' (albeit very likely) cocaine use is completely two faced.
MET Chief Backs Moss Drug Probe (BBC News Online; Wednesday 21st September 2005)