Ajax is already enabled by default.  The code has been added to the default.aspx.vb file.  If your module supports ajax and you enable partial rendering from the appropriate user control of the module, dnn will automatically add or wrap the entire page in an ajax update panel.

Paul

Thank you for your responses!

However what is confusing my is that Gemini for the feature DNN-5226 included in 4.5.0 says this: "(...) A Host Setting has also been added to Enable Partial Rendering which wraps the Administrative modules in UpdatePanels for a more rapid user experience.(...)"

I've trying the administrative modules and them don't show any AJAX behaviour. 

Did I misundestood the issue on Gemini?

thanks,

dani