I don't think this is anything new. I believe I first saw something about fishing with an RC boat years ago. I seem to recall seeing an RC boat that actually came set up for fishing. I think it was meant to be more for little kids to have fun catching small bream, etc. close to the bank than anything else, though - kind of like in the last video that jimboksg posted. I honestly think it looks kind of fun and probably requires more skill that some might think. After all, you have to know how much line to let out depending on how deep or shallow they are biting, you have to know when to activate the reel to avoid too much slack and when to just let the fish run. You have to be aware of when you need to move the boat, etc.
Personally, in addition to the RC boat and the RC reel I would want one more RC item. I would have a small, RC swing arm with an X-Acto blade, razor blade or scalpel blade mounted to it set up perpendicular to the line. That way if I caught something too big I could activate the swing arm, move the blade against the line and cut the line before my RC boat sank.