A district court judge has ruled that "an IP address is not a person" in mass litigation against BitTorrent users identified by IP address. In the case "VPR International v. Does" judge Harold Baker mentioned the practice of going after Wi-Fi router owners for wrongdoing by others who pick up their signals, resulting in dropping cases. A person or company or party needs to be identified as having done something wrong to be a target of either criminal or civil litigation, he seems to be saying. The TorrentFreak story is here.
Also (getting back to the first topic), I've noticed that a Verizon MI-Fi Secure will time out and turn itself off if a computer using it hibernates (but not if it is turned off properly). This may be a security feature. Ordinary wireless routers don't seem to do this.