I'm setting this up at the moment. No, not a public IT iodine server, just a little server on my Mac Mini behind my FON router. It's not that difficult to set up. On the N800 side you don't need to do anything since that's going to be the client.
I would suggest everyone who is interested to check out the following URL's:

http://blog.cg.nu/?p=18
http://www.recalinux.com/core/?q=node/2
http://dev.kryo.se/iodine/wiki/HowtoSetup

and apply the information to your own environment. I'm not Linux savvy, but even i understand what they say, so....

when i have it working on my Mini i will try to implement the same on the FON router so i can switch off the Mini without losing the tunnel.

Ton.