Thanks, that was enough information to jog my memory of the little paperwork that originally came with the BT GPS device, indicating in my case 0000 as the default pin.
(Did not have paperwork with me, but suddenly jumped out into my consciousness, entered it and it works; BT GPS Paired)

I never needed to Pair my BT GPS device for use with Maemo Mapper on my Nokia 770 & N800, but with the map application provided with OS 2008 Beta, I had to pair the device to make software see the GPS. (Interested for feature comparison purposes only, MM is my preferred app)