I have a G1 with the standard G1 unlimited internet and 400 texts/month plan with T-Mobile. What I'm wondering is...if I get an unlocked and jailbroken iPhone, will I be able to put my sim card (from my G1) and use it without any problems on the iPhone?

If anyone is actually using an iPhone with T-Mobile, can you confirm if you're able to download stuff from the app store without any problems? 3G is not important to me. Thanks.