Sure thing!
RSS-feeds are XML formated outputs of something - in this case your guestbooks (or at least the 10 last added entries). If you are using a certain software called an aggregator (such as FeedReader -
http://www.feedreader.com/) or even the Firefox or Opera web-browsers, you can easily view the "feeds" of many webpages quickly, without having to actually visit all the sites. This saves you time.
Blogs and forums frequently make use of RSS feeds for this purpose. I wanted to make this feature available, primarily for guestbook owners, so that they can see if there are any new entries in the guestbook without having to actually visit it.
Let me know if you have any other questions regarding RSS or how it works.
BTW, you can also view the RSS feed of this forum here:
http://forum.ultraguest.com/external.php?type=xml