I think that the concern with pine is the resins that it loves to give off- pitch could taste pretty poor in a brew. Or wonderful, perhaps, but seems doubtful.
That said, I made mine from pine (it was around), dried the portion which goes into the kettle, did the soak/sand routine, and kissed it with a torch to really get it dry. Avoided knots in the kettle portion as well. Only used it for two batches, but so far, not seeing any effect...although oak or maple would have been less work!