It should be possible (and I will check later with mine) to turn on internet sharing and create an ad-hoc network. The card will then get an ip address which is in the same range as the host computer and all should be fine.

Even without ad-hoc capability, as long as it will work with a non-internet connected router that’s good enough for me. I have a airport extreme router, which is *tiny* and can easily be carried along with the laptop.

I am a big fan of the whole idea of the eye-fi cards, it’s really a fantastic idea.

None of the Eye-Fi Cards support ad-hoc networking. While it is true that you can not use an Eye-Fi Card in an ad-hoc network, it is not true that you have to have and “internet connected” router to wirelessly transfer your photos to a computer.

You need to have a wireless router and an internet connection to initially configure your Eye-Fi Home, Share or Explore Cards. However thereafter if all you want to do is transfer files to your computer over your wireless network you do not have to have a “internet connected” router. Once the card is set up all you need is for the Eye-Fi Card and computer to be on the same network created by a wireless router.
Many Eye-Fi users want to use an Eye-Fi Card when there is no internet connectivity or Wi-Fi available. For these customers we recommend using a travel router. Here are a couple of links that you may find helpful.

http://photojojo.com/uncut/2007/11/07/how-to-download-photos-with-eye-fi-without-an-internet-connection/
http://photojojo.com/uncut/2007/11/07/maximize-your-eye-fi-range-for-event-shooting/