Client CallBack in ASP.NET 2.0

Whidbey, a tool to bring user and developer closer, more easily. Sounds good, does'nt it? Anyway, I heard about the call back functionality they were implementing. Sounded too good. Great feature, etc. etc. Played around with it and it looked really good, useful, etc.etc. Then started the thought process. How are they doing it??? I had heard about another way, using an ActiveX object called XMLHTTP.
Then some guys discussed about whether client callback worked on browsers such as Mozilla, the doubt level increased especially when a bug was reported on Visual Studio bug tracker. So I explored, it was quite simple. When I included code to get a event reference to the callback functionality ASP.NET included a script (.js) file. I got out this file and opened it in good, old TextPad..... Goodness, gracious it looked extrememly familiar. Have a look. So I guess technology is not new but just implementation has been changed, for the better????? Maybe.......... :)