National Review Online has a good point here. Obama's past drug use was rightfully declared off-limits during the campaign. Everyone on the left seemed to agree that was appropriate, so bludgeoning Limbaugh over his own drug use is lame.

You could make a decent argument that Limbaugh's behavior was more shocking (in light of this wildly hypocritical statement, for example), but that's really beside the point. The fact that past drug use is no longer a landmine on the campaign trail is an encouraging signal that our political culture has matured beyond the finger-wagging of the past. If we want it to stay that way, then there must be a bi-partisan truce when it comes to trashing someone's character for using drugs.

If you're actually discussing drug policy, that might be different, but just blatantly citing past drug use as evidence that someone's an asshole is not cool. This isn't about Rush Limbaugh, it's about moving beyond the "I didn't inhale" era so that we can have public discussions of drugs and drug policy that aren’t politicized and perverted to the point of absurdity.