This article describes a control which can host a UserControl. It allows to Ajaxify a user control without any code change. The main benefit is that when refreshing its content, it does not instantiate the full page but only the contained user control. Most of the ASP.NET features (at least the ones that I tested) are supported: viewstate, controlstate, postback events, validators... Moreover, one of the cool features of this control is allowing UserControl to do cross-domain Ajax postback.
