If you never had an iPhone, you really can't say what features the new iPhon will or will not have. The 3Gs has many features (finally) that you could only get via jailbreak (mms, video, cut and paste).
Originally Posted by weezerguy187
I personally jailbroke my V1 so I could get screen shots, tethering capability, and the ability to theme. Screen shot capability was estabished in OS 2.0. You still can't officially tether, but with jail break you can.
The iPhone Dev Team has jail broken OS 3.0 for existing 3G devices. Not clear what is lurking behind the 3Gs hardware. After all, it will have its own OS version. If jail breaking is important to you, I would recommend finding a 3G device.