OSGi provides a standard configuration mechanism called Config Admin. This allows the location of configuration information to be decoupled from the code that requires the configuration. Configuration is passed through to services via a Map or Hashtable, and they can then configure themselves appropriately.
As with other parts in OSGi, this can also be dynamically updated. When the configuration source changes, an event can flow through to the service or component in order to allow it to reconfigure itself.
Config Admin itself is an OSGi service, and it may be supplied by different configuration agents. A de facto standard is Apache Felix's FileInstall, which can also be used to install bundles into an OSGi runtime.
FileInstall is available from the Apache Felix site at http://felix.apache.org as well as Maven Central. Download org.apache.felix.fileinstall-3.2.8.jar and import it into Eclipse as a plug-in project by navigating to File...