Automatically post something I write for one blog to the other blogs

I am using Wordpress 3.0 so I am not sure if this applies to previous versions of WP or not.

In the WP admin, go to Tools > Import. Then you'll see a list of import tools you can install and use.

What facebook uses is called oEmbed - there is an oEmbed plugin for wordpress, and it shouldn't be super hard to create one for blogger.

In addition, if you need more than the sites that officially support oEmbed, you can try oohEmbed, which supports a very long list of sites.