Generating XSD schemas from JAXB types in Maven?

Here's the win:

<plugin>
    <groupId>org.codehaus.mojo</groupId>
    <artifactId>jaxb2-maven-plugin</artifactId>
    <version>1.3.1</version>
    <executions>
        <execution>
            <goals>
                <goal>schemagen</goal>
            </goals>
            <phase>generate-resources</phase>
            <configuration>
                <includes>
                    <include>com/myproject/model/*.java</include>
                </includes>
                <outputDirectory>${project.build.directory}/schemas</outputDirectory>
            </configuration>
        </execution>
    </executions>
</plugin>

Improving on Naftuli Tzvi Kay's answer, I found it more convenient to use the now-current version 2.2 of the jaxb2-maven-plugin, like in this sample (as the 2.x version requires slightly different configuration):

<plugin>
    <groupId>org.codehaus.mojo</groupId>
    <artifactId>jaxb2-maven-plugin</artifactId>
    <version>2.2</version>
    <executions>
        <execution>
            <goals>
                <goal>schemagen</goal>
            </goals>
            <phase>generate-resources</phase>
            <configuration>
                <sources>
                    <source>src/main/java/com/foo/model/xml</source>
                </sources>
                <outputDirectory>${project.build.directory}/schemas</outputDirectory>
            </configuration>
        </execution>
    </executions>
</plugin>

See the plugin documentation for more details.