It is, but I think the really interesting part is to making the connection seamless and as direct as feasible. e.g. how do you do it on one end of the spectrum if neither the embedded device or the users device has access to the internet, but they can see one another via bluetooth and wifi?

I think an app makes a lot sense to initially bridge embedded devices (that may only support simple web interfaces or even lower level network messages) to smartphone browsers (which are currently oriented to handling fairly rich web interfaces from full servers).

But where it should get really interesting is if you make the app support a generic enough protocol that you don't need an app-per-device type, but the app/protocol can handle a wide range of generic embedded device interfaces without requiring a full featured / high performance web server on every embedded device. After that you could basically get the protocol supported at the browser/os level and the app disappears.