Delorme Inreach SE @ 190 grams is a good choice if you are in the market for a PLB or Satellite Phone. It is only slightly dearer (and heavier) than a stand-alone PLB (& so much cheaper than lighter than an Iridium Extreme) but with two way SMS messaging functionality from anywhere on earth. Whenever you send someone an SMS with it your exact GPS location goes with the message. The service is also much cheaper than a satellite phone.
You can also load maps on it and use it as a GPS. You can pair it with your mobile phone to make it even more user friendly. It has a tracking function which can notify your friends every few minutes of your exact location (people can even ‘ping’ you to trigger your location) – and of course it has an SOS button which will bring emergency services if you need rescuing. The fact that it has two-way messaging will mean that unnecessary rescues will be reduced enormously.
The internal battery will last a trip up to 10 days (ie over hours), but of course can be recharged on the go eg with one of these: http://www.theultralighthiker.com/charging/ More details here: http://www.inreachdelorme.com/product-info/inreachse.php and here:http://www.theultralighthiker.com/get-lost-get-found-plbepirb/
This is another really handy lightweight (50 gram) device for keeping in touch: http://www.theultralighthiker.com/gotenna/
As are these: http://www.theultralighthiker.com/emergency-cb-radios/
To see what else I carry in my pack see: http://www.theultralighthiker.com/a-gorilla-in-the-hand/