For those of you considering upgrading your security/recovery methods for your bikes, you may want to look at the new LoJack system.
It is still the vehicle recovery system as before but they have now added a "Early Warning Recovery System." This part consists of a small football shaped key fob that is tied into the bike when you ride. If the fob is not near the bike and the bike is moved LoJack is notified and they will call your cellphone,homephone and send an email or text message to warn you that your bike is being moved. To start the tracking you will still notify the local police and they will locate your bike.(hopefully)
One advantage to this system is that you do not need to be near the bike to get a call about your bike being moved. Most audible pager systems only notify you if you are within 1/2 mile or so.
This new system is about $100 more than the old LoJack. I don't know if you can upgrade an older LoJack or not.