These subscriber clients will allow you to subscribe a site or service, via the hub, to a feed from the publisher:

For more information on the subscribers and alternative frameworks and CMS systems, visit http://code.google.com/p/pubsubhubbub/wiki/SubscriberClients.

There are also a number of publisher clients available for use. These will allow you to implement feeds on a site that subscribers will be able to subscribe to via a hub. They will work to notify the hub of new updates from the publisher.

For more information on the publisher clients and alternative plug-ins that are available, visit the publisher list at http://code.google.com/p/pubsubhubbub/wiki/PublisherClients.