It was a high level thought, as I have a USB GPS reciever lying around in a box.
Problem I can see with Bluetooth ones based on what I'm reading is that the app has to have the capability to get the signal via bluetooth, (unless Andrioid 2.3.new has now got that built into the OS?, in which case my phone choice next week is as good as made
I've also been reading from hiking forums that a high proportion of the built in ones are pretty useless in trees, which based on my trusty Garmin 12's performance means they'll be navigating round chocolate teapot territory in my inside pocket.
As for marine apps, I'm waiting patiently for MemoryMap to bring out their 'droid app as I have the entire UK charts courtesy of a fantastic deal last Christmas. Just a shame I never noticed the OS 1:50k deal that was on the week before.....
I have a few waiting on the PC for a "working trial", mostly weather & tide related.