Running websites on Microsoft Office SharePoint Server 2007 and you would like to give the end-user a richer user experience by using AJAX?
To AJAX enable your MOSS site collection, several steps need to done as described by Mike Ammerlaan's Integrating ASP.NET AJAX with SharePoint blog post. All those steps needed to modify the web.config can be done with one easy action by using Ajaxify MOSS.
To AJAX enable the website http://myMossEnvironment install Ajaxify MOSS and run:
stsadm -o addajax -url http://myMossEnvironment
It supports both ASP.NET AJAX 1.0 and the ASP.NET AJAX build-into ASP.NET 3.5. Make sure you have MOSS Service Pack 1 installed.
More information on the Ajaxify MOSS CodePlex site.