Thx!
Your data is speard over the net in small chunks and encrypted and in multiple copies. No farmer can actually know what they are storing would need all chunks and key to open the encryption. Kinda like dropbox only you are not trusting your data to a single corporation, but instead to all farmers who have no clue they are holding your data (or at least a small portion of it).
This is all of course assuming that Maidsafe will work perfectly one day and scale unlimitedly. Which I have doubts about, but it would really by my dream to see it.