The GA designation means "customers can now create, share, and use Access apps with full confidence and the same level of guaranteed availability as the rest of Office 365," according to a February 3 post on the Office blogs site. While there were Access 2013-centric apps in the Office/SharePoint stores as of last year, "until now, Access apps were in preview and weren’t supported under the Office 365 service-level agreement (SLA) and compliance standards," Microsoft officials conceded.
Access apps are now generally available for Office 365 Small Business, Midsize, Enterprise, and Education customers, officials said. But Access apps for Office 365 Government customers are still considered to be in preview. The Access apps are available via the SharePoint Store, according to the blog post (but from what I can tell, also seem to be available through the Office Store).