Revealed by running org.jboss.test.profileservice.test.ProfileServiceUnitTestCase.
If there is e.g. an empty -ds.xml file it will re-deployed over and over again even though it's not been modified.

org.jboss.deployers.spi.DeploymentException: Error creating managed object for vfsfile:/E:/cvsroot/trunk/build/output/jboss-5.0.0.Beta3/server/profileservice/deploy/testHqldbDS-ds.xml
 at org.jboss.deployers.spi.DeploymentException.rethrowAsDeploymentException(DeploymentException.java:49)
 at org.jboss.deployers.spi.deployer.helpers.AbstractParsingDeployerWithOutput.createMetaData(AbstractParsingDeployerWithOutput.java:232)
 at org.jboss.deployers.spi.deployer.helpers.AbstractParsingDeployerWithOutput.createMetaData(AbstractParsingDeployerWithOutput.java:199)
 at org.jboss.deployers.spi.deployer.helpers.AbstractParsingDeployerWithOutput.deploy(AbstractParsingDeployerWithOutput.java:162)
 at org.jboss.deployers.plugins.deployers.DeployerWrapper.deploy(DeployerWrapper.java:169)
 at org.jboss.deployers.plugins.deployers.DeployersImpl.doInstallParentFirst(DeployersImpl.java:853)
 at org.jboss.deployers.plugins.deployers.DeployersImpl.install(DeployersImpl.java:794)
 at org.jboss.dependency.plugins.AbstractControllerContext.install(AbstractControllerContext.java:327)
 at org.jboss.dependency.plugins.AbstractController.install(AbstractController.java:1309)
 at org.jboss.dependency.plugins.AbstractController.incrementState(AbstractController.java:734)
 at org.jboss.dependency.plugins.AbstractController.resolveContexts(AbstractController.java:862)
 at org.jboss.dependency.plugins.AbstractController.resolveContexts(AbstractController.java:784)
 at org.jboss.dependency.plugins.AbstractController.change(AbstractController.java:622)
 at org.jboss.dependency.plugins.AbstractController.change(AbstractController.java:411)
 at org.jboss.deployers.plugins.deployers.DeployersImpl.process(DeployersImpl.java:498)
 at org.jboss.deployers.plugins.main.MainDeployerImpl.process(MainDeployerImpl.java:506)
 at org.jboss.system.server.profileservice.hotdeploy.HDScanner.scan(HDScanner.java:290)
 at org.jboss.system.server.profileservice.hotdeploy.HDScanner.run(HDScanner.java:221)
 at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:417)
 at java.util.concurrent.FutureTask$Sync.innerRunAndReset(FutureTask.java:280)
 at java.util.concurrent.FutureTask.runAndReset(FutureTask.java:135)
 at java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.access$101(ScheduledThreadPoolExecutor.java:65)
 at java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.runPeriodic(ScheduledThreadPoolExecutor.java:142)
 at java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.run(ScheduledThreadPoolExecutor.java:166)
 at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(ThreadPoolExecutor.java:650)
 at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:675)
 at java.lang.Thread.run(Thread.java:595)
Caused by: javax.xml.bind.UnmarshalException
 - with linked exception:
[org.xml.sax.SAXParseException: Premature end of file.]
 at javax.xml.bind.helpers.AbstractUnmarshallerImpl.createUnmarshalException(AbstractUnmarshallerImpl.java:315)
 at com.sun.xml.bind.v2.runtime.unmarshaller.UnmarshallerImpl.createUnmarshalException(UnmarshallerImpl.java:506)
 at com.sun.xml.bind.v2.runtime.unmarshaller.UnmarshallerImpl.unmarshal0(UnmarshallerImpl.java:215)
 at com.sun.xml.bind.v2.runtime.unmarshaller.UnmarshallerImpl.unmarshal(UnmarshallerImpl.java:190)
 at com.sun.xml.bind.v2.runtime.unmarshaller.UnmarshallerImpl.unmarshal(UnmarshallerImpl.java:241)
 at org.jboss.resource.deployers.ManagedConnectionFactoryParserDeployer.parse(ManagedConnectionFactoryParserDeployer.java:100)
 at org.jboss.resource.deployers.ManagedConnectionFactoryParserDeployer.parse(ManagedConnectionFactoryParserDeployer.java:47)
 at org.jboss.deployers.vfs.spi.deployer.AbstractVFSParsingDeployer.parse(AbstractVFSParsingDeployer.java:112)
 at org.jboss.deployers.spi.deployer.helpers.AbstractParsingDeployerWithOutput.createMetaData(AbstractParsingDeployerWithOutput.java:225)
 ... 25 more
Caused by: org.xml.sax.SAXParseException: Premature end of file.
 at org.apache.xerces.util.ErrorHandlerWrapper.createSAXParseException(Unknown Source)
 at org.apache.xerces.util.ErrorHandlerWrapper.fatalError(Unknown Source)
 at org.apache.xerces.impl.XMLErrorReporter.reportError(Unknown Source)
 at org.apache.xerces.impl.XMLErrorReporter.reportError(Unknown Source)
 at org.apache.xerces.impl.XMLVersionDetector.determineDocVersion(Unknown Source)
 at org.apache.xerces.parsers.XML11Configuration.parse(Unknown Source)
 at org.apache.xerces.parsers.XML11Configuration.parse(Unknown Source)
 at org.apache.xerces.parsers.XMLParser.parse(Unknown Source)
 at org.apache.xerces.parsers.AbstractSAXParser.parse(Unknown Source)
 at org.apache.xerces.jaxp.SAXParserImpl$JAXPSAXParser.parse(Unknown Source)
 at com.sun.xml.bind.v2.runtime.unmarshaller.UnmarshallerImpl.unmarshal0(UnmarshallerImpl.java:211)
 ... 31 more