Over the years, I've conditioned myself to use the Uri class
when surfacing web URLs in my application. Early versions of
Silverlight couldn't bind an image source directly to an instance
of a Uri because they lacked an appropriate type converter; the
usual workaround was to change the property to a string type.
Subsequent versions Silverlight added that capability and the
converter. For example. Given an instance of the following model
class as the data context:
public class Tweet
{
public string Message { get; set; }
public Uri Image { get; set; }
}
In Silverlight, you can bind in XAML like this:
<Image Source="{Binding Image}" />
In the current version of Windows 8/WinRT XAML, you can't bind
image sources directly to Uris, but there's a nice way to do it by
using property element syntax and and a BitmapImage class. It's
more verbose, but may be just the ticket if you need to bind to
Uris and not strings, and can't change, or don't want to change,
your [view]model.
<Image>
<Image.Source>
<BitmapImage UriSource="{Binding Image}" />
</Image.Source>
</Image>
The team is aware of this difference, and have it in their
backlog of things to prioritize for future revs. In case you're
sharing markup or anything between WinRT XAML and Silverlight, it's
good to know this more verbose approach works in both.