I had same problem with Eclipse 3.7.2 (Indigo) and maven 3.0.4.
In my case, the problem was caused by missing maven-resources-plugin-2.4.3.jar in {user.home}\.m2\repository\org\apache\maven\plugins\maven-resources-plugin\2.4.3 folder. (no idea why maven didn’t update it)
Solution:
1.) add dependency to pom.xml
<dependency>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-resources-plugin</artifactId>
<version>2.4.3</version>
</dependency>
2.) run mvn install from Eclipse or from command line
3.) refresh the project in eclipse (F5)
4.) run Maven > Update Project Configuration... on project (right click)
JAR file is downloaded to local repository and there are no errors in WS.