What types of technologies could this work with?
You could use whatever driver API you want for driving your System Under Test (SUT)... JNarrate only wraps that with a Fluent API that encourages you to write the behaviour specifications (acceptance tests) at the appropriate level of abstraction.
In the Examples, I've written a WebBrowser facade around WebDriver but that is purely illustrative. JNarrate is a test-authoring framework that can be used to wrap any technology whether it's a web-automation framework (like WebDriver) or a Swing driver.
JNarrate could be used within other frameworks too, if you so desired - such as JBehave. I intend on using it within Narrative Fixture which is a Fit Fixture (work in progress) that also follows the given/when/then format for writing acceptance tests.