hCards are a microformat that describe your contact information in a manner that can be parsed by machines, but is also human readable and therefore can be included inline with any html that you make.
Pingerati is run by Technorati and is a service that notifies other services (such as mine) of updates to peoples sites and blogs.
At the moment pingerati pings me whenever a hCard is updated on a page. I record this information and only use it in some stats at the moment.
To get your hCard into my stats I would suggest that you simply make sure that you ping pingerati at the following url
http://pingerati.net/ping/[url that is updated] (details can be found at: http://www.pingerati.net/about/). This can be done by configuring your blog writer to include the pingerati ping service with any other pings it does.
I would like to see Microformats being taken up because there are a lot of cool services that can be provided once the data can be understood by machines.
Once topicala has enough information there are some services that I will be adding to make topicala a lot better.
If you are wondering how to make an hCard simply visit http://microformats.org/code/hcard/creator