Able accounts were authorized by federal law by adding §529A to the Internal Revenue Code in December of 2014. They are actually allowed to be operative by 1-1-15. However, they are not yet in effect in CT (effective 10-1-15) or NY (probably effective around 2-15) and you can't set one up.
To be operative, the state where you reside has to pass implementing legislation.
Connecticut passed the legislation and it was signed into law (Public Act 15-80) on 6-19-15, however it is not effective until 10-1-15. New York passed the legislation (S 4472), however as of 8-14-15, the governor has not yet signed it into law. NY's law is effective 180 after it is signed into law.
Both laws establish the enabling legislation and exempt the accounts from state taxation.
In addition, the IRS has to issue regulations implementing the law and fleshing out the details. It finally issued this guidance Notice 2015-18 on 3-10-15 with advance notice it intended to issue proposed Regulations. There are some good things in this Notice and some bad things. First, they generally have an expansive view of the expenses which can be reimbursed. In addition, they allow the states to set up plans now, even though the rules are not out yet. Second, they generally have burdensome administrative requirements.