One of the new features in 3.5 SP1 is stringformat. The usage is pretty simple. So following are simple snippets showing its use
<TextBox Text="{Binding Path=Double, StringFormat=F3}"/>
<TextBox Text="{Binding Path=Double, StringFormat=Amount: {0:C}}"/>
<TextBox Text="{Binding Path=Double, StringFormat=Amount: \{0:C\}}"/>
<TextBox>
<TextBox.Text>
<Binding Path="Double" StringFormat="{}{0:C}"/>
</TextBox.Text>
</TextBox>
<TextBox>
<TextBox.Text>
<MultiBinding StringFormat="{}{0:F2} = {1:D}">
<Binding Path="Double" />
<Binding Path="Date"/>
</MultiBinding>
</TextBox.Text>
</TextBox>
<TextBox>
<TextBox.Text>
<Binding Path="Date" StringFormat="{}{0:MM/dd/yyyy}"/>
</TextBox.Text>
</TextBox>
<ListBox Background="Beige" ItemStringFormat="F3">
<sys:Double>1.11122</sys:Double>
<sys:Double>2.11345</sys:Double>
</ListBox>
<GroupBox Background="AliceBlue" Content="{Binding Path=Double}"ContentStringFormat="F4"
Header="{Binding Path=Double}" HeaderStringFormat="F5"/>
<Label Content="{Binding Path=Double}" ContentStringFormat="{}{0:E2}"/>
<GridView>
<GridViewColumn Header="Date"
DisplayMemberBinding="{Binding XPath=Date, StringFormat=D}" />
This feature makes life a lot more easier when it comes to formatting.. So have fun with it.