Removing xsi/xsd namespaces in .NET XML Serialization

// Cull all the namespaces.
// You may want to add your own here though, so replace .Add with .Add("prefix", "namespace");
var namespaces = new XmlSerializerNamespaces();
namespaces.Add(string.Empty, string.Empty);

// While we're at it, that XML version declaration can go to hell too.
var settings = new XmlWriterSettings { OmitXmlDeclaration = true };
var serializer = new XmlSerializer(dataType);
using (var memoryStream = new MemoryStream())
{
    using (var writer = XmlWriter.Create(memoryStream, settings))
        {
            serializer.Serialize(writer, this.Data, namespaces);
                // And do whatever you want with writer at this point.
    }
}