Yes, it's still very much illegal federally. It's still a Schedule I controlled substance. The federal banking system / IRS refuses to interact with marijuana businesses, the postal service won't mail ads for it, the DEA continues to raid growers, etc, etc.
Edit: as others have pointed out, I was incorrect in lumping in the IRS with the rest of the federal banking system. The IRS does indeed accept money from marijuana businesses. There are other parts of the federal banking system that are not so "accepting", for instance: http://www.denverpost.com/2016/01/05/judge-tosses-denver-mar...
Edit: as others have pointed out, I was incorrect in lumping in the IRS with the rest of the federal banking system. The IRS does indeed accept money from marijuana businesses. There are other parts of the federal banking system that are not so "accepting", for instance: http://www.denverpost.com/2016/01/05/judge-tosses-denver-mar...