It is important to note that if you use singleton="false" in spring you will get an exception, for example:
org.springframework.beans.factory.xml.XmlBeanDefinitionStoreException: Line 33 in XML document from ServletContext resource [/WEB-INF/subasta-servlet.xml] is invalid; nested exception is org.xml.sax.SAXParseException: cvc-complex-type.3.2.2: Attribute 'singleton' is not allowed to appear in element 'bean'.
To get rid of this exception you have to change singleton="true" to scope="singleton" for more information on which scopes are available in spring I suggest visiting http://static.springsource.org/spring/docs/2.0.x/reference/beans.html#beans-factory-scopes.