Structured Blogging is a way to get more information on the web in a way that's more usable. You can enter information in this form and it'll get published on your blog like a normal entry, but it will also be published in a machine-readable format so that other services can read and understand it.
Think of structured blogging as RSS for your information. Now any kind of data - events, reviews, classified ads - can be represented in your blog.
So let's try this. Here's my hCard:
Hi, I'm Richi Jennings, of Richi Jennings Associates, where I'm the Principal. I'm based in Berkshire, United Kingdom. You can call me on +44.7789.200701 or leave a message on +1.806.993.5712. You can also email me at richi.hcard@richi.co.uk, or IM me using AIM/YIM/Skype.