What Neil means is that as long as you visit the App Store to legally buy and download the apps, you will be fine. The act of jailbreaking is legal.
The key here is that jail breaking does not affect the fact that you must pay for all apps you buy from the App Store. Yes, there are free apps, and you can get those without paying for them - but they are only free because the developer has offered them for free, NOT because you used tools (gained from jail breaking) to make them free (e.g. to steal them).
Bottom line: Any attempts at using a jail break to get apps for free that normally would be paid for is an illegal activity. It is theft, plain and simple. As such, it is not welcome here (or any where - and should never enter your moral code).