Tethered vs Untethered
 

Naast de uitleg op onze Wiki geeft Update #2 op de iPhone Dev Team blog extra uitleg over (un)tethered jailbreaks:

Update #2: The notion of a “tethered” jailbreak is pretty new to many people, so here’s a quick rundown on what to expect:

1. If you’re on an iPhone3G, old-bootrom iPhone3GS, or non-MC ipt2g, life is easy. redsn0w installed an untethered jailbreak and so nothing below applies.
2. “Tethered” does not mean you cannot boot at all without PC/Mac assistance. If you have not installed any tweaks that hook into important programs like SpringBoard or CommCenter, your device will actually boot. However, jailbreak programs like Cydia won’t work (and Cydia may still have a white icon). Also, certain built-in apps that had to be moved by Cydia will fail (Safari being the most noticeable example).
3. If you’ve installed MobileSubstrate tweaks that hook into SpringBoard or other important programs, your boot will actually fail (you’ll get stuck at the Apple logo). You need to use redsn0w to “Just boot tethered right now”.

Remember, @comex and others are working on a way to untether the 4.2.1 jailbreak. Meanwhile, the above 3 points hopefully will make it all seem less confusing :)