I've thought about this a lot over the past few years. I think it'd be awesome to be able to compile your web app into a bundle that gets loaded by some Objective-C server.
That being said, I think the performance improvement would have to be substantial to get me to switch from a scripting language.
That's exactly what I did (see other response), and it works pretty well for the most part. The bundle gives you both a nice container to deploy, along with the ability to pull assets out of it with a relative bundle path, just like on iOS/Mac.
Launchd works really well for keeping your server process running too, zero issues there.
The performance was really good, with the right libraries involved and some tuning you could have something really nice, but very few groups are focusing on it at the moment :\
That being said, I think the performance improvement would have to be substantial to get me to switch from a scripting language.