This would be an awesome addition in my opinion.

Seeing the comment right there in the mail and not having to navigate back to the site to see it.

I love this place for its comments and I am always happy when a new "New Comment for XYZ post" mail arrives in my inbox.
However I get most of these on my phone while I am out and about somewhere and I always feel like I have to rush to the nearest internet cafe to see what is going on. Having the comment included in the mail would really make that it easier to decide wether that is necessary.

What do you think?