This plugin does not seem to be available from the WordPress.org site or in the plugin search. If you can find it, let me know. I think it has probably disappeared off the site because the author is not supporting it. You can download the follow plugin I use here:
Download the Follow Plugin zip file
(Install via WP Dashboard -> Plugins -> Install New -> Upload)
There is a follow tab/button in the lower right corner of every “free” wordpress.com blog.
When people subscribe, they get an email every time a post or a page is published. It’s a great feature for keeping your audience engaged!
If you have a hosted blog and you would like a follow button here are step by step instructions for the installation. FYI – I used GVO hosting in this video.
There may be minor differences if you have a different host…
The picture to the right shows what the box looks like when you click on it. You can try it out for yourself on this blog. Look in the lower right hand corner.