So what can your phone do in a semi-tethered jailbreak state? Well you’ll be able to make calls, send texts, run stock apps (the default apps that come with the phone except Safari, Mail (you can use third party alternatives though), you can’t use any jailbreak tweak, app, or Cydia until you boot tethered (there’s a chance of getting stuck in a respring loop).
While you won’t be able to use a whole lot of functions, it’s still much better than a tethered jailbroken phone. If you’d like more details on how to semi-tether jailbreak your phone, head here. Take note that it won’t work on the iPhone 4S – developers are still trying to figure it out.