Hmm... had my iPhone jailbroken ages ago but went back to normal as I didn't actually get that much from it to be honest. But this sounds really appealing. Not got iPad yet as Apple haven't told us in the UK anything, but I had decided to go for Wifi-only model and get something like Pay as you go Mifi device as that would be cheaper that buying the 3G iPad model. But if I can use the 3G I'm already paying for on my iPhone, then that makes it even better. I'd even consider buying an iPad with larger capacity then.
It's been a while since I tried jailbreaking. What's the latest thing? Blackrain or something? Is that the one that has MyWi?