I think H is definitely back in a big way. But, as far as drug of the decade, if we're going to compare with E in the nineties, and coke in the eighties, pharmaceutical opiates are probably it. The thing is that those drugs, E and coke were definitely considered cool, and are somewhat expensive so it is almost a type of status symbol. Pharms go along with that, they have become more available and used by younger and younger kids, and generally are more expensive(at least than H). the path of opiates doesn't usually start with dope, but does often end there.
Regarding meth, in my opinion meth is more like crack was in the 80s, and PCP in the 90s. They were commonly used, widely available, and cheap, but didn't neccessarily have the 'cool,' or status symbol aspects associated with coke, or E. In the context you are talking about, the allure of the drug is a big consideration. The drug that defines a decade may not be the most used, most sought after, or most widely available, but the one with the most fascination, the drugs the white kids in the suburbs keep hearing about.
Media attention is a big factor as well. I know that meth gets a lot of media attetion, but the media meth gets is a lot different than the type of media pharmaceuticals receive. In stories about meth, you see poor white people with no teeth who live in trailer parks, have not teeth left, and just blew off their right arm and leg maning a meth lab in a cooler in the middle of the woods. How many celebrities have gone to rehab for meth? How may rappers have 'meth' tattooed on their necks? How many covers of Time or Newsweek had big, sexy, glossy photos of meth on the cover? The way the media portrays the users of a drug has a lot to do with the way the drug is pereived. Not necessarily by people on a harm reduction site on the web, but the general public anyway.
So I guess that i would say meth is the pcp and crack of this decade, as pills are the ecstasy and coke. Just my opinion...
btw. Those kids in chi who can't find meth, ask some gay guys you know who go out a lot. it's all over gay clubs and saunas and whatever in the city, most cities actually.