Pretty slick. Wish it worked better in TextMate though. I'll keep this in my toolbox, but for now I think it's better to think outside the box with something like HAML which can capture these shortcuts in your actual code, so its easier to traverse. HTML has a ton of useless information, seems better to strip all that out and only focus on the underlying content and structure.
It looks clever, but I don't think I'd use it. I don't really want another layer of abstraction between my keyboard and my HTML -- I'd sooner write it directly, closing tags and all.
Here's a similar project supporting the same syntax written in python that woks in vim.<p><a href="http://github.com/rstacruz/sparkup" rel="nofollow">http://github.com/rstacruz/sparkup</a>