It's a little different in Washington. No home growing allowed except for the currently allowed medical usage. Producers have to be licensed, paying $1000 annually for the privilege. All regulated by the Washington State Liquor Control Board. Other growing is still illegal.
Possession decriminalization goes into effect next month, and the process for licensing and sales has to be worked out by December 2013. 25% excise taxes on wholesale and retail sales, earmarking some revenue for purposes that include substance-abuse prevention, research, education, and healthcare with the rest going to the state general fund.
But the feds of course will still have their say in the matter. Figure it will be a while before the pot stores open up next to Jamba Juice in the local strip malls. But the retail store franchises might be an interesting investment opportunity. Or a lot of small mom-and-pop businesses, depending on how they write the regulations.