We don't currently have a feed or widget for this yet, although it's a great idea. I can think of a couple ways you could do this today:
you could write a Clearspace plugin that creates the feed, I'd be happy to help you get started in the API if you're interested
you could write some code that requested the people page that has users sorted by status and grab the content of the div with ID = jive-people-results (this would probably be brittle and would require more work on your part, but it's one way you could do it)
you could have our PS team do the customization for you.
Yes, I'd be interested in writing a plugin for this. If you can get me started that would be much appreciated.
Don't start thinking that I forgot about you writing a plugin for this. Here's a start:
create a Clearspace plugin
create an action that extends RssActionSupport and that implements FeedAction
take a look at the source for StatusLevelLeadersAction for an example of how to get the top users
take a look at the source for RSSCombinedContent for an example of how to create a feed
create your action and deploy it
get your feed by going to http://example.com/clearspace/youraction.jspa
Ping me if you run into any problems.
I would love to have this for Jivespace and Ignite, so if someone does create it, sharing is good