Wow, this is exactly what I have wanted, ever since I got my first iPod — except I wanted the exact opposite.
What I really want is for the blocker to go the other way — I want to be able to sync without charging. (I realise a cable probably couldn’t do that, I assume it would have to be done at the hardware level.)
The reason for this is my great care for battery life. In the manual of one of the first mobile phones I owned, it said quite explicitly that I shouldn’t charge the phone until it was fully uncharged, and I have taken that to heart ever since.
But I want to be able to sync my iPhone, to get the latest podcasts, apps, and calendar updates. So I strongly urge Apple — or Matias, if it’s possible for them to do so — to create a way to allow for syncing, and not charging.
(Via Typical Mac User.)