i'll post this for posterity sake. the problem was that for this dev environment both sites were running on tomcat. when tomcat was starting spring was trying to cache the VM_global_library.vm file and bombed because it couldn't load it from itself yet. what clued me in was when i stopped tomcat it threw a java socket error - because it couldn't open the socket to load the template.
the whole point of using urlresourceloader would be to load from a different server or box so i imagine this problem would not be likely to happen in a more life-like environment.
here's the final config that worked:
<bean id="velocityConfig" class="org.springframework.web.servlet.view.velocity.VelocityConfigurer">
<prop key="MYO.resource.loader.root">http: //foobar/content/vm_templates/</prop>