this is from an old thread of mine:
The present perfect continuous is used for:
1. to emphasize the duration of an event (often includes "since", "ever since", "for").
Your sentence emphasizes the "hour" (duration) but it may or may not continue to wait; we don't know or don't care, which is why we use this structure. It is the "hour" that has completed and that is what we are talking about, nothing else.
2. to connect a continuous activity in the recent past to the present:
e.g. Her eyes are red. She has been crying.
In this case, she probably has just finished crying but we can see "evidence" of her actions.