String format in Xaml

When you need to concatenate some strings in a TextBlock you can use the tag like Run.

Silverlight 4 has introduced an useful feature to make this more easy: StringFormat.
Now you can put more informations in a single element.

The code is very simple:

<TextBlock Text="{Binding Username, StringFormat='Hello \{0\}'}" />
<TextBlock Text="{Binding Temperature, StringFormat=\{0\}°}" />

and it works also with numbers and dates:

<TextBlock Text="{Binding Value, StringFormat=\{0:n2\}}" />
<TextBlock Text="{Binding Value, StringFormat=\{0:c2\}}" />
<TextBlock Text="{Binding Date, StringFormat=f}" />

You can check more details in the Kunal's blog