The 3rd beta preview release of Tapestry 5.4 is now available.
While not an actual release candidate, beta previews like this one are high-quality builds that pass all of Tapestry's extensive automated tests. You are encouraged to try out this beta preview and let us know how it's working.
If you're using Maven (or Gradle or Ivy, etc), you'll need to add the Apache staging repository to your configured list of Maven repositories first:
<repository>
    <id>apachestaging</id>
    <name>Apache Staging Repository</name>
    <url>https://repository.apache.org/content/groups/staging</url>
    <layout>default</layout>
</repository>

and here's the dependency:

<dependency>
    <groupId>org.apache.tapestry</groupId>
    <artifactId>tapestry-core</artifactId>
    <version>5.4-beta-3</version>
    <type>jar</type>
</dependency>

There is also a Maven archetype available, so you can build a quick little starter project as described at Getting Started, but specifying an alternative catalog:

-DarchetypeCatalog=https://repository.apache.org/content/groups/staging