Opportunity zones and opportunity funds were established by Congress as part of Tax Cuts & Jobs Act that was passed in December 2017. Governors of every state and U.S. territory (and the mayor of Washington DC) nominated their opportunity zones in spring 2018. IRS published the finalized list of designated opportunity zones [PDF] in July.
But many developers and investors are still anxiously awaiting more detailed regulations from the IRS, which are promised later this year.
Update 10/19/18: Treasury has issued its first tranche of proposed rules on opportunity zones.