Not sure why you are fading the status div twice.
I get it now. You are trying to show the div and then fade it away. Try this:
$("#status").html("You are now registered!").show().fadeTo(7000, 0);
Or you could use fadeIn and fadeOut to make them both fade, like this:
$("#status").html("You are now registered!").fadeIn(500).fadeOut(7000);
SERVER SIDE
To do it on the server side you would use the RegisterClientScriptBlock method of the ScriptManager class like so:
ScriptManager.RegisterClientScriptBlock(Me, Me.GetType(), "clientScript", "$(function() { $('#status').html('You are now registered!').fadeIn(500).fadeOut(7000); });", True)
The first parameter would be the page you are using it on. Then the type, which you can use me.GetType() to get, then a name for the method which isn't really important what you call it, and then the actual jQuery code. The last parameter is a boolean as to whether to include script tags or not. If you put them in the jquery code, set it to false, otherwise keep it true.
Also, you may need a ScriptManager control between the form tags on the page you use this on. And this was done using VB code.