For the record, here is a working pom for a dead-simple webapp I just created using the standard maven archetype. Managed to deploy onto a JBoss-as-6 (community) freshly downloaded.

working-cargo-jbossas6-pom.xml

<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
	xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/maven-v4_0_0.xsd">
	<modelVersion>4.0.0</modelVersion>
	<groupId>net.batmat</groupId>
	<artifactId>testdeploywebapp</artifactId>
	<packaging>war</packaging>
	<version>1.0-SNAPSHOT</version>
	<name>testdeploywebapp Maven Webapp</name>
	<url>http://maven.apache.org</url>
	<dependencies>
		<dependency>
			<groupId>junit</groupId>
			<artifactId>junit</artifactId>
			<version>3.8.1</version>
			<scope>test</scope>
		</dependency>
	</dependencies>
	<properties>
		<jboss.version>6.0.0.Alpha9</jboss.version>
		<cargo.plugin.version>1.0.6</cargo.plugin.version>
	</properties>
	<build>
		<finalName>testdeploywebapp</finalName>
		<plugins>
			<plugin>
				<groupId>org.codehaus.cargo</groupId>
				<artifactId>cargo-maven2-plugin</artifactId>
				<version>${cargo.plugin.version}</version>
				<configuration>

					<container>
						<containerId>jboss6x</containerId>
						<type>remote</type>
					</container>

					<configuration>
						<type>runtime</type>
						<properties>
							<cargo.logging>high</cargo.logging>
							<cargo.servlet.port>8080</cargo.servlet.port>
							<cargo.hostname>localhost</cargo.hostname>
							<cargo.remote.username>admin</cargo.remote.username>
							<cargo.remote.password>admin</cargo.remote.password>
						</properties>
					</configuration>

					<deployer>
						<type>remote</type>
						<deployables>
							<deployable>
								<groupId>${project.groupId}</groupId>
								<artifactId>${project.artifactId}</artifactId>
								<type>war</type>
								<properties>
									<context>/${project.build.finalName}</context>
								</properties>
								<pingURL>http://localhost:8080/${project.build.finalName}/index.jsp</pingURL>
								<pingTimeout>5000</pingTimeout>
							</deployable>
						</deployables>
					</deployer>

				</configuration>
				<dependencies>
					<dependency>
						<groupId>org.codehaus.cargo</groupId>
						<artifactId>cargo-core-tools-jboss-deployer-5.1-and-onwards</artifactId>
						<version>${cargo.plugin.version}</version>
					</dependency>

					<dependency>
						<groupId>org.jboss.jbossas</groupId>
						<artifactId>jboss-as-profileservice-client</artifactId>
						<version>6.0.0.Final</version>
						<type>pom</type>
					</dependency>

					<dependency>
						<groupId>org.jboss.jbossas</groupId>
						<artifactId>jboss-as-client</artifactId>
						<version>6.0.0.Final</version>
						<type>pom</type>
					</dependency>
				</dependencies>
			</plugin>
		</plugins>
	</build>
</project>