A little while ago, there was a thread on Ben Forta's blog (I can't quite remember it) where someone was looking for practical examples of using Event Gateways.  They just saved the day in my neck of the woods, and here's why:

I've got an application where a common user interaction updates records in Verity.  You never know how many Verity records may get updated:  maybe one, maybe ten thousand...<p>[<a href="http://www.firemoss.com/blog/index.cfm?mode=entry&entry=4A09E05F-E081-2BAC-698C0D1F8CBD8D35">Read more on Joe Rinehart's blog</a>]</p>