I've been looking at this the last few days also. Good timing!
The other piece of the puzzle for me is whether there's a way to automate the sending of the blog alert emails via Marketo? Or integrating the subscription form capture with another automated tool like Feedburner (or hopefully something better than Feedburner, which we're still using...).
It looks to me like they're capturing and sending the emails via Marketo. They're on a different template but sent out an hour or two after the post, so i'm thinking they might be manually creating an email and campaign for each new post... which is more cumbersome than what i want. Hoping there may be a more streamlined way - any ideas appreciated!