Thanks @ChadNouis, I finally found out that I was setting my svn user name and pw before the properties file for them was loaded.
It was hanging because the repository requires a username/pw but none were supplied.
Seems like something that either the server would reject or the client would realize has timed out, but that was the issue.
The offending configuration:
<typedef resource="org/tigris/subversion/svnant/svnantlib.xml"
classpathref="svnant.classpath"/>
<!-- create svnSetting from properties...that don't exist yet -->
<svnSetting id="svn.settings" username="${svn.username}" password="${svn.pw}"
javahl="false" svnkit="true" failonerror="true"/>
<!-- properties file loaded after svnSetting created...d'oh -->
<property file="svn-credentials.properties"/>
<target name="commit">
<svn refid="svn.settings">
<commit file="${webcontent}/version.properties"
message="commit version from build.xml by ${user.name}"
/>
</svn>
</target>