We'll it appears iDrumTech is being sued by Tune-bot for copyright infringement.
Check out the details with the link above.
I'm not really sure how you can patent a method/technology that uses frequency to tune an instrument. What about guitar tuners, pitch pipes or your ears. In reality, these all use frequencies in some way.
Eric Rosebrock, maker of iDrumTech, is a complete mess right now. He changed the iPhone version of iDrumTech to Donation-ware. He needs to retain a patent lawyer for representation and is accepting donations. Follow iDrumTech on Facebook for some of the back story and any future updates.
-Tim