They worked on tracks here and there("B*tch Please, "Imagine"), but haven't come close to releasing a joint project. Fear not. To let Snoop tell it, Dre producing one of his upcoming albums isn't that far-fetched.
"What is the possibility of a Dr. Dre-produced album from Snoop Dogg?" Snoop pondered during a sit-down with BET.com. "I'd say about a 90% chance it can happen. You know, the 10% that lies out there is about availability as far as from Dr. Dre, not me, because I know and understand that I’m good, but when I’m with Dr. Dre, I’m great."
Source - http://www.bet.com/Music/news/Snoopdoggsaysdrdrealbumislikely_musicnews_03.18.10.htm