Can somebody explain the differences, status and future of the various ASP.NET AJAX libraries and toolkits?

I'm confused about the differences and relationships between the various Microsoft ASP.NET AJAX components/libraries/toolkits and particularly the naming of them.

It starts off relatively simple with ASP.NET AJAX itself:

• ASP.NET AJAX 1.0 (available for ASP.NET 2.0 in a separate package called ASP.NET 1.0 Extensions)
• ASP.NET AJAX 3.5 (included with ASP.NET 3.5)
• ASP.NET AJAX 4.0 (included with ASP.NET 4.0)

Then come the various projects on CodePlex and elsewhere:

ASP.NET AJAX Control Toolkit (aka Original Ajax Control Toolkit)

• Samples
• CodePlex
• It seems that the September 2009 Release is the final release of the Original Ajax Control Toolkit and that it's been superseded by...

Ajax Control Toolkit in ASP.NET Ajax Library

• It looks like the old ASP.NET AJAX Control Toolkit has now become part of a larger ASP.NET Ajax Library but is still maintained seperately on CodePlex. This release is in beta at time of writing so presumably if I want to use the "Control Toolkit" I should stick with the September 2009 Release of the Original ASP.NET AJAX Control Toolkit
• CodePlex

Microsoft Ajax Library Preview

• Is this the same as the ASP.NET Ajax Library mentioned above just with a confusing name variation?
• Is the "Control Toolkit" included in Preview 6 and is it o开发者_如何学JAVAlder newer or older than the code in Ajax Control Toolkit in ASP.NET Ajax Library?
• CodePlex
• Microsoft ASP.NET Ajax Wiki - note the inconsistent insertion of ASP.NET into the name

Links to useful articles, roadmaps would be useful.

ASP.NET supports an AJAX framework for all three versions with different assemblies. The Ajax control toolkit was an add-on open source library that adds a variety of useful extenders and a few useful controls. They support 2.0, but a little while ago just started to release for 3.5. The preview is for ASP.NET AJAX 4.0, to illustrate what is coming, so it won't be labeled preview in the final release.

The final release in 4.0 will allow you to work completely on the client-side by making available a dynamic script loader to load the client-side components you need from the Ajax Control Toolkit, so you won't need any server side components, unless you want to still develop that way. Perfectly valid option.

HTH.