Just been playing around with this a little and thought I'd share my experience.
I'm using a Garmin eTrex.
Pocket Warrior
MapPoint.
The basics:
Garmin output set to NMEA
Pocket Warrior GPS enabled.
I configured Pocket Warrior, configured the eTrex and had them both ready to go. When PW was up and running I plugged in the Garmin and the fields in Longitute and Latitude were immediatly populated.
Piece of cake!
Next. Take a wander around a couple of streets and detect a few APs.
Next. Save the file and upload it to the PC.
All going smoothly, but Map Point was complaining that it could not match the data in the file. So I had to manually play with the data in the TXT file before importing. The addresses were in the format "W xx.xxxx: where Map Point wanted "-xx.xxxx". So I played around with that and very soon had it all up and running.
Not sure yet if I can get the GPS to output the co-ordinates in the exact format yet, I believe that it's actually the way PW is pulling displaying the data that is the issue. Anyway, need to play with that some more.
No funny tricks apart from the formattting (which I'm sure there is a workaround for the GPS first.
Other than that, went ultra smoothly. Off out of town for a few days so it'll be fun to map some other part of town. :)