I've used Pilot MyCast on a Treo 650 since I started my primary
training in March '05. The primary benefit to me is as an on-the-spot
device to update me on the weather. A number of times, while I was
pre-flighting, my instructor (a NAFI Master CFI) asked to see it to
consult the radar picture. I particularly like the fact that it loops
radar and satellite pictures to give you a better idea of what's going
on instead of just a static picture. In addition to the functions Jay
mentions, it will allow you to enter a route and give you weather along
it, does a lightning map, a weather map, and visible and infrared
satellite pictures.

Unfortunately, their website doesn't do a good job of displaying all
the functions, and is light on hard information, IMHO. Also, the
installation instructions for my Treo were not quite right, but their
tech support helped me straighten it out.

I understand the FCC prohibits using cell phones in flight, so it
should be used as a ground-based tool only. Moreover, I've been told
that some cell phone companies, in order to manage the load on their
system, detect when a user is rapidly switching cells as when flying,
and will not establish a network connection. Some folks I know who
have tried their cellphones in flight get a signal, others don't (note
to FCC - I'm not naming any names :-).

I may reconsider my decision on MyCast if I get a Garmin GPSMap 396,
which gets XM weather, but for right now I am planning to renew my
subscription. I think it cost me something like $150 per year (they
advertise something like $129 but it's apparently higher on the Treo
platform. It's a good tool.

Wiz