If you're asking this just to make something look good on your resume, the answer is no.
If you are excited about observing patient-physician relationships, and eager to learn something new everyday as a result of observing, then the answer is yes.
Yes, it does help your med school application, because it is something of an unspoken rule. In that sense, it won't help you much, but it'll probably hurt you not to have it.
If so, then the answer is not really. You pretty much HAVE to shadow to have a shot at getting into medical school. A lack of shadowing can really hurt your application, though. Medical school admission committees will want to know how you know you want to be a physician if you haven't even observed what a physician actually does.