This had to do with an <exclusion> in the shale-spring pom. Removing it and switching to Spring 1.2.5 which has good poms (things marked optional) fixed it.
[DEBUG] Generating c:\svn\struts\shale-m2-reorg\shale-spring\target\site\integration.html
[INFO] Generate "Continuous Integration" report.
[DEBUG] Generating c:\svn\struts\shale-m2-reorg\shale-spring\target\site\dependencies.html
[INFO] Generate "Dependencies" report.
[DEBUG] While downloading jstl:jstl:1.0
This artifact has been relocated to javax.servlet:jstl:1.0.
[DEBUG] While downloading xerces:xerces:2.0.2
This artifact has been relocated to xerces:xercesImpl:2.0.2.
[DEBUG] While downloading xml-apis:xml-apis:2.0.2
This artifact has been relocated to xml-apis:xml-apis:1.0.b2.
[DEBUG] While downloading xerces:xerces:2.0.2
This artifact has been relocated to xerces:xercesImpl:2.0.2.
[DEBUG] While downloading xml-apis:xml-apis:2.0.2
This artifact has been relocated to xml-apis:xml-apis:1.0.b2.
[INFO] ------------------------------------------------------------------------
[ERROR] FATAL ERROR
[INFO] ------------------------------------------------------------------------
[INFO] null
[INFO] ------------------------------------------------------------------------
[DEBUG] Trace
java.lang.NullPointerException
at org.apache.maven.artifact.resolver.DefaultArtifactResolver.resolve(DefaultArtifactResolver.java:82)
at org.apache.maven.artifact.resolver.DefaultArtifactResolver.resolve(DefaultArtifactResolver.java:63)
at org.apache.maven.project.DefaultMavenProjectBuilder.findModelFromRepository(DefaultMavenProjectBuilder.java:467)
at org.apache.maven.project.DefaultMavenProjectBuilder.buildFromRepository(DefaultMavenProjectBuilder.java:225)
at org.apache.maven.report.projectinfo.DependenciesReport$DependenciesRenderer.getMavenProjectFromRepository(DependenciesReport.java:456)
at org.apache.maven.report.projectinfo.DependenciesReport$DependenciesRenderer.printDescriptionsAndURLs(DependenciesReport.java:392)
at org.apache.maven.report.projectinfo.DependenciesReport$DependenciesRenderer.printDescriptionsAndURLs(DependenciesReport.java:429)
at org.apache.maven.report.projectinfo.DependenciesReport$DependenciesRenderer.printDescriptionsAndURLs(DependenciesReport.java:429)
at org.apache.maven.report.projectinfo.DependenciesReport$DependenciesRenderer.printDescriptionsAndURLs(DependenciesReport.java:429)
at org.apache.maven.report.projectinfo.DependenciesReport$DependenciesRenderer.printDescriptionsAndURLs(DependenciesReport.java:429)
at org.apache.maven.report.projectinfo.DependenciesReport$DependenciesRenderer.renderBody(DependenciesReport.java:277)
at org.apache.maven.reporting.AbstractMavenReportRenderer.render(AbstractMavenReportRenderer.java:65)
at org.apache.maven.report.projectinfo.DependenciesReport.executeReport(DependenciesReport.java:97)
at org.apache.maven.reporting.AbstractMavenReport.generate(AbstractMavenReport.java:101)
at org.apache.maven.plugins.site.ReportDocumentRenderer.renderDocument(ReportDocumentRenderer.java:67)
at org.apache.maven.doxia.siterenderer.DefaultSiteRenderer.renderModule(DefaultSiteRenderer.java:239)
at org.apache.maven.doxia.siterenderer.DefaultSiteRenderer.render(DefaultSiteRenderer.java:115)
at org.apache.maven.plugins.site.SiteMojo.renderLocale(SiteMojo.java:124)
at org.apache.maven.plugins.site.SiteMojo.execute(SiteMojo.java:92)
at org.apache.maven.plugin.DefaultPluginManager.executeMojo(DefaultPluginManager.java:412)
at org.apache.maven.lifecycle.DefaultLifecycleExecutor.executeGoals(DefaultLifecycleExecutor.java:534)
at org.apache.maven.lifecycle.DefaultLifecycleExecutor.executeGoalWithLifecycle(DefaultLifecycleExecutor.java:475)
at org.apache.maven.lifecycle.DefaultLifecycleExecutor.executeGoal(DefaultLifecycleExecutor.java:454)
at org.apache.maven.lifecycle.DefaultLifecycleExecutor.executeGoalAndHandleFailures(DefaultLifecycleExecutor.java:306)
at org.apache.maven.lifecycle.DefaultLifecycleExecutor.executeTaskSegments(DefaultLifecycleExecutor.java:273)
at org.apache.maven.lifecycle.DefaultLifecycleExecutor.execute(DefaultLifecycleExecutor.java:140)
at org.apache.maven.DefaultMaven.doExecute(DefaultMaven.java:322)
at org.apache.maven.DefaultMaven.execute(DefaultMaven.java:115)
at org.apache.maven.cli.MavenCli.main(MavenCli.java:256)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
at java.lang.reflect.Method.invoke(Method.java:585)
at org.codehaus.classworlds.Launcher.launchEnhanced(Launcher.java:315)
at org.codehaus.classworlds.Launcher.launch(Launcher.java:255)
at org.codehaus.classworlds.Launcher.mainWithExitCode(Launcher.java:430)
at org.codehaus.classworlds.Launcher.main(Launcher.java:375)
[INFO] ------------------------------------------------------------------------
[INFO] Total time: 24 seconds
[INFO] Finished at: Sat Jun 10 17:07:23 GMT-07:00 2006
[INFO] Final Memory: 21M/45M
[INFO] ------------------------------------------------------------------------