There is no law that says you must use a web browser with a web-based service. Ideally, all you would need is a stable REST URL to use with a POST request. An iPod will do what you need as long as you use the proper tools. It is true that having a scanner send input via a text field is an old-school, tried-and-true kludge, but it was never anything more than a kludge. Such things do tend to break when you change platforms. Why use Sencha Touch if you are only supporting one, HTML-based platform anyway?
You could make a great inventory control system that works on any platform. Or you could kludge one up that works with one specific platform. With the kludge, you will save a few hours in up-front development costs in exchange for many cumulative hours of trouble during operations. I will leave it as an exercise for the reader to guess which option would be the choice for typical corporate IT.
