In our SVN repo, we store tags like this:
trunk project_a project_b branches project_a branch_x branch_y project_b tags proje
The release plugin now supports the tagNameFormat configuration option, which defaults to @{project.artifactId}-@{project.version}. In your case, you could do something like:
tagNameFormat
@{project.artifactId}-@{project.version}
org.apache.maven.plugins maven-release-plugin 2.3.2 @{project.artifactId}/@{project.version}