I just installed latitude on my windows mobile phone. It certainly could be a good thing for social networking, but not a good replacement for SPOT. I will use it when kayaking on the ocean.
Of course there has to be cellular service available to use it, but that should not be a problem up high in the Northeast (or along the coast).
I would not even think of using it unless you have a *unlimited* data plan.
If your phone has GPS and you enable your GPS, the precise position will be reported.
Otherwise your reported location appears to be the location of the cell phone tower that the phone is using.
I turned the GPS off on my phone and watched my location appear on the map...it was the location of the cell towers up on the opposite ridge. As I moved to the other side of the house, the blue dot moved by a mile or two to the location of another cell phone tower up by Home Depot. So the conclusion is that you need a GPS enabled phone to get an accurate position.
With the GPS in my phone turned on, my location was a blue dot right on top off the house I am in (in satellite photo view)
Here is a video which gives a quick overview and use-cases of Latitude. Friends can track you on their PC:
http://www.youtube.com/watch?v=Q-Oq-9enE-k
Here is a video which tells you how to control your privacy with Latitude:
http://www.youtube.com/watch?v=nXmcoadcoJY&feature=channel
If you are looking to install the application (Latitude is a part of Google Maps- not a special application) on your phone its:
http://www.google.com/latitude
That should redirect you to the proper place depending on what device/browser you are using.