I'm trying to understand the cloud sub-element in RSS 2.0

[lkrubner]

I apologize for being a bit dense, but I'm trying to wrap my head
around the sentence

"Its purpose is to allow processes to register with a cloud to be
notified of updates to the channel, implementing a lightweight
publish-subscribe protocol for RSS feeds."

When they say "cloud" do they just mean a program running on a server?
more info:

=============== =============== ======

http://blogs.law.harvard.edu/tech/rss

<cloud> sub-element of <channel>

<cloud> is an optional sub-element of <channel>.

It specifies a web service that supports the rssCloud interface which
can be implemented in HTTP-POST, XML-RPC or SOAP 1.1.

Its purpose is to allow processes to register with a cloud to be
notified of updates to the channel, implementing a lightweight
publish-subscribe protocol for RSS feeds.

<cloud domain="rpc.sys .com" port="80" path="/RPC2"
registerProcedu re="myCloud.rss PleaseNotify" protocol="xml-rpc" />

In this example, to request notification on the channel it appears in,
you would send an XML-RPC message to rpc.sys.com on port 80, with a
path of /RPC2. The procedure to call is myCloud.rssPlea seNotify.