Depending on the eavesdropper's skill and the eavesdrop-ee's wisdom stat, the eavesdropee may or may not notice that he/she is being eavesdropped upon; every time someone in the room performs an action/says something there is a chance that the eavesdropper will be noticed.
If there is a door in the way, it will be harder to eavesdrop, but it will also be harder to notice the eavesdropper.
And, finally, if someone comes into the room where the eavesdropper is eavesdropping, it will be immediately obvious that the eavesdropper is eavesdropping--perhaps unless an "improved eavesdropping" feat or some such is introduced. But one step at a time.
I realize this is probably mostly wishful thinking and not likely to be introduced in the near future, but I think it would add an additional dimension to roleplay.




