This is something I'm also confused about. Does anyone have the answer? It seems like the thing to do is make "i"-everything and sell the rights to Apple. What if Apple wants to make a home automation system? They have to talk to iHome, the iPod dock company (though iHome is a legitimate corporation with good products).
You need to have a logical reason for using/trademarking the name other than the fact that you want to sell it to Apple. I believe it's quite similar to the way domain names are registered. If you can't prove you have an intention to actively use the name (domain name) then you have to forfeit ownership.
If anyone legitimately tried to use an "iProduct" name they had best have one hell of a logical reason for it that differentiates themselves from Apple altogether. I also doubt one would be able to trademark the name without sufficient reason/proof. Correct me if I'm wrong here?