Actually that satellite thingie is not that hard or mega expensive. Check out cubesats. Little solar panels two android phones(or sth similar, android phones just an example for cheap and ready to go) poack it full with sd storage and with some kind of transmission down to earth, voila: almost indestructible bitcoin node ;=)http://en.wikipedia.org/wiki/CubeSat
Oh well, starting from 100k$ with shooting into space.... not that cheap, but compared to huge satellites a bargain.
Yeah and the launch costs are just the beginning.
An android phone would last about 5 minutes in space. You have to use "space hardened" composites for your CPU, RAM etc, normal silicon chips simply don't operate in the radiation of space. NASA recently upgraded to space hardened 486 chips, so they may have some old space hardened 386 stock laying around somewhere you could buy for a few hundred grand?
Then there's the issue of communication. Cubesats dont have antenna dishes or long range comms capability, so they have extremely limited communication with earth. Generally radio is used, and the satellite is in communications range for a few minutes per day as it passes over a particular spot on the earth. Communication is strictly one-way and limited a to a burst of a few hundred kilobytes at best.
I suppose you could place the Cubesat in a geostationary orbit, meaning it would more or less stay in communications range at all times, but only from one particular place on the earth, which makes it all a little pointless, and I'm not sure how far out it would have to be from the earth to be geostationary, and if you could effectively communicate when the sat was that far out...
TL;DR - There's a few interesting applications you could use a cubesat for, but I don't think hosting a Bitcoin wallet is among them.