"UpdateSourceTrigger=PropertyChanged" equivalent for a Windows Phone 7 TextBox

Is there a way to get a TextBox in Windows Phone 7 to update the Binding as the user types each letter rather than after losing focus?

Like the following WPF TextBox would do:

<!-- language: lang-xaml -->

<TextBox Text="{Binding Path=TextProperty, UpdateSourceTrigger=PropertyChanged}"/>

I took Praetorian's answer and made an extension class that inherits TextBox so you don't have to muddle up your view's code behind with this behavior.

C-Sharp:

<!-- language: lang-cs -->

public class TextBoxUpdate : TextBox
{
    public TextBoxUpdate()
    {
        TextChanged += OnTextBoxTextChanged;
    }
    private void OnTextBoxTextChanged(object sender, TextChangedEventArgs e)
    {
        TextBox senderText = (TextBox)sender;
        BindingExpression bindingExp = senderText.GetBindingExpression(TextBox.TextProperty);
        bindingExp.UpdateSource();
    }
}

VisualBasic:

<!-- language: lang-vb -->

Public Class TextBoxUpdate : Inherits TextBox

    Private Sub OnTextBoxTextChanged(sender As Object, e As TextChangedEventArgs) Handles Me.TextChanged
        Dim senderText As TextBox = DirectCast(sender, TextBox)
        Dim bindingExp As BindingExpression = senderText.GetBindingExpression(TextBox.TextProperty)
        bindingExp.UpdateSource()
    End Sub

End Class

Then call like this in XAML:

<!-- language: lang-xaml -->

<local:TextBoxUpdate Text="{Binding PersonName, Mode=TwoWay}"/>