As linked and referred to earlier, Randy Brown of Open Artifact has already come up with a Purple Number Plugin for WP. You can see the implementation on his own blog. In simple terms, it allows hotlinking to a specific paragraph in a WordPress article.
Here is the link to the hack.
That implementation is really annoying to me. The purple color distracts my reading. I think if you’re going to implement hotlinking in each paragraph you have to be really careful with your design and choice of colors.
I’ve updated PurpleNumbers to v1.0. You can find it and details here.
They are called Purple Numbers for a reason.
But, never fear… CSS is here. Just simply change the color inside the plugin.
Hope this helps.