I’ll also plug NS Basic/App Studio - which essentially works by translating the form designer and VB-style code into HTML5/Javascript, so the web apps it creates can be run by Android, iOS, and Blackberry version 6 and later, as well as any other browser that supports the HTML5/Webkit standard.
If you know vb.net you might be inclined to pick up c# if you haven’t already dabbled. It would allow you to use the same IDE, though, obviously syntax will differ.
There is Mono for android which allows you to develop for android using visual studio and c# with support for a lot of neat .net stuff like LINQ. they also have Mono Touch which allows you to target the iphone/iPad.
It connects to PhoneGap to wrap up native apps - I haven’t experimented with that yet. I just use the iPhone Safari ‘add this page to home screen’ shortcut.