When I surfing on, I found a control that named "Partial Update Panel". This sounds like Microsoft Update Panel but its not.

This request to a user control and get back the render html then render it own inner area. This means, you can asynchronously load a partial of your page.

Just check it out, you will understand it.

 

http://partialupdatepanel.codeplex.com/

 

It has some issues and difficulties on using but its good begining.

 

hope this help.