I'm working on converting the cargo program to Silverlight. This means it will work on Macs and any browser that supports the Silverlight plugin. It will still be a program you download to run, but it is sandboxed and runs in your browser.
The classes are about 75% good as is. However, some things I was using (datasets, arraylists) are not supported in Silverlight, so I'll be converting them. And I'll be working on the 3rd iteration of the classes.
The interface should be a LOT nicer - I've been using XAML at work and it is really sweet in terms of presentation, customizing and data binding. All sorts of ideas are bouncing through my brain.
I'll keep things posted here.