Certainly there are periods of time when it is possible to jailbreak a device over the internet(!!), times when it is possible locally, and times when it it, for months, not possible at all.
My point (poorly made perhaps) is that I have heard people say, "Oh, don't worry about Apple's walled garden, anyone with technical knowledge can be out of it as soon as they want, with jailbreaking". However, there are clearly long periods of time when that isn't true.
Incidentally: I found myself in exactly the same position with iPad 2. It seemed as if it was all hinging on release date of the next iteration of the OS and I did wonder at tine if Apple had perfected their game of cat and mouse.
