Wouldn't it be much nicer if my website could just tell all these different sources that my content had changed, at the time of publishing instead of having to do it manually?
This is exactly what a web ping does. A web-ping is a small request that goes out from your blog to alert services that are interested in your data that your content has changed. This ping goes out to the search engines and the new breed of portals called aggregators. An aggregator is a place that brings together content from all different sources and arranges them into related categories depending on what their audience is looking for.
A web ping happens automatically for blogs at Blog-City without the author having to do a single thing. Services such as Technorati, Yahoo, Ping-o-matic etc all get notifications that your blog has changed, and they will then come and look at your blog to get the latest information.
The constant craving of new data from these services has meant a standardisation of the ping protocol. There now exists a large network, called Feedmesh, that takes your web ping and shares it amongst all the service hosts that want to know your data has changed. This includes all the large search engines as well as all the smaller specialised aggregators. This reduces the amount of web pings that have to be sent out. For example instead of 10 web pings being made on every blog update, only 1 web ping is generated and that web ping is then shared with everyone on the Feedmesh network. Even the big operators want to save bandwidth and resources!
But really what does it mean for you and your blog?
Basically it means a greater potential audience for your data. You are alerting the search engines that your blog has changed and needs re-craweled. You are alerting the aggregators that your blog has new data and they should come and read it and start using it, hopefully encouraging their users to click on it and come to your blog. It's about increasing your blog's visibility beyond that of just your own mailing list and regular readers.
All without you having to do a single thing; all you need to worry about is producing good quality blog posts.