Ring 1.6.0 has been released. It's been ten months since the first beta release and almost eight weeks since the first release candidate.
The most significant addition to this release has been asynchronous handlers. This allows handlers to be defined with three arguments, and provide the ability to pause the handler while waiting for I/O, without blocking a thread.
The response body has also been changed to use a protocol rather than a static list of allowed types. This allows you to access the response output stream directly and write your own output methods for custom types and records.
Other bug fixes and additional functionality is covered in the project's changelog.