I was just informed that Mendelssohn now stocks the GNS 5870 in Australia:
GNS 5870 GPS Bluetooth receiver for iPad
We have not tested this one, but there is no reason to suspect it won't work...
If anyone already has one, we'd love to hear about your experiences.
I'll be in Oshkosh next month and I suspect I will investigate and buy samples of a fair few interesting ways to use the iPad in the cockpit. I am sure there will be plenty on offer this year.
EDIT: I have just ordered one. Will let people know how it goes.