this thread piqued my curiosity, so this morning i emailed inquiries to
the folks at MacENC as to whether their system might work using the new 3G iPhone -- which, as you may have read, includes GPS -- to interface with a laptop. the answer is a qualified "no" -- but they also alluded to a new iPhone app in the works:
"The iPhone GPS does not have a NMEA interface so it would not work as the GPS for MacENC. That being said we do have an iPhone app in the works that will work stand alone or as a MacENC repeater. Technically it would be possible to make the iPhone send out its GPS position via TCP/IP and have MacENC pick that up, but then you would quickly run the iPhone battery down."
so to clarify, i asked whether the app being developed would allow the iPhone to function like a Garmin handheld unit, for instance, with the maps loaded in the unit itself (taking advantage of that 16GB iPhone memory). they answered:
"Yes! iNavX will make the iPhone work much like a Garmin handheld GPS. The charts are the NOAA RNC (raster) charts and they are downloaded to the iPhone via wifi or cell connection. If all of the charts were downloaded it would take 5 GB of storage, however most folks need less than a dozen charts for their primary sailing area."