bill - 2:20 am on Feb 9, 2009 (gmt 0)

Is feedburner a service that updates aggregators?

FeedBurner is a feed management system. It does have a ping service to notify services of changes to your feed. You could also ping most of these manually.

Also: so in principle if I simply change the content of the stuff between the <description> tags the aggregators will recognize the altered content and update the subscription?

RSS 2.0 uses <pubDate> and Atom uses <updated> to indicate new items.