Jeff let me know about Baby Monitor for BlackBerry that he just started using. Trustbe released this app over a month ago and it allows you to stream audio from one BlackBerry to another over Wi-Fi, 3G, EDGE, and more. You just select one device to be the parent station and one to be the baby monitor. Jeff let me know that he just repurposed one of his old BlackBerry’s lying around into a easy baby monitor for a few bucks.
If you are in need of a Baby Monitor check out Trustbe’s solution in App World for $3.99. Trustbe recommends just using the same BlackBerry ID to download the app onto two devices without paying twice but that would eat into your yearly device changes in App World.