Releases are available from Maven Central:

<dependency>
  <groupId>at.molindo</groupId>
  <artifactId>wicketstuff-merged-resources</artifactId>
  <version>4.0.0</version>
</dependency>

Current snapshots are available from Sonatype OSS:

<repository>
  <id>sonatype-nexus-snapshots</id>
  <name>Sonatype Nexus Snapshots</name>
  <url>https://oss.sonatype.org/content/repositories/snapshots</url>
  <releases><enabled>false</enabled></releases>
  <snapshots><enabled>true</enabled></snapshots>
</repository>

<dependency>
  <groupId>at.molindo</groupId>
  <artifactId>wicketstuff-merged-resources</artifactId>
  <version>4.0.1-SNAPSHOT</version>
  <type>pom</type>
</dependency>

Builds are performed by Travis CI: