Today Apple updated the download page of its developer website with an option to request access to the TestFlight beta version of iOS 12's Shortcuts app. This was first discovered by Steve Troughton-Smith:
— Steve Troughton-Smith (@stroughtonsmith) July 5, 2018
The release notes for beta 1 of Shortcuts confirm that Workflow users who install the new beta will have their existing workflows imported into Shortcuts, as Federico previously noted.
Up until now, the Shortcuts app has made no appearance in existing iOS 12 beta releases. This was unsurprising because Shortcuts is going to be released as an App Store download, but it was unclear whether beta testers would be given the chance to gain access to the Shortcuts app before its public release. Fortunately, if you're an Apple developer, the answer is officially yes.