Not to mention currently the CastleLink is a .NET application and there aren't any phones capable of running the application, let alone as neil noted the USB issues, etc. Only phone that has .NET to some degree is WinPhone7 which the apps are built using Silverlight which is a subset of .NET; it doesn't support all the features of .NET. I haven't seen anyone yet that has MONO (the opensource implementation of .NET) running on Android yet; granted I haven't looked in-depth, but nothing has come up in general perusal of usual programming haunts.