iBookstore allows publishers to sell books as DRM-free, so Tor books should be OK from it. Subterranean Press' books are DRM-free in iBookstore too. Unfortunat

iBookstore allows publishers to sell books as DRM-free, so Tor books should be OK from it. Subterranean Press' books are DRM-free in iBookstore too. Unfortunately, other's aren't (I only bought a few books there and it's a 50/50 split so far) and you don't have any way of knowing before buying.