From what I've read you Bluetooth your iPad to the 275 and then it wirelessly downloads to your Garmin Pilot App which then uploads it to flygarmin.com
Another reason they force us to have a subscription to Garmin Pilot. I use Foreflight for day to day but already have a subscription to Garmin Pilot just to control my XM radio on my Garmin 52.
I'm ordering my 275 EIS this week so I'll be able to teat this out in about 20 weeks.