I find it really difficult when I am trying to respond to a DP message on my smartphone and I recently came across this app on blackberry/iphone/android called tapatalk and it integrates forums (that have installed the tapatalk module) nicely on a phone. I spent a few hours integrating my company forum and it works great. I would love to see DP offer something for mobile users.
Most likely you will see a custom Digital Point app (it's not super high on the priority list, but it is on the list).