have you been looking at sharepoint (yeah, yeah, okay "moss")? wanted to add some ajaxified love to those new interfaces? or perhaps some of your own web parts.
take a look at some comments from mike ammerlaan on the topic. in a recent post, mike talks about integrating asp.net ajax with sharepoint (see he doesn't even use moss). there are some tips on extending the sharepoing web.config with the appropriate elements, yada yada.
in addition to that, eric schoonover writes about the AjaxBasePart and provides examples and code for you to use.
with these two resources it should be enough to get you started -- or at least thinking.
tags: sharepoint, moss 2007, moss, sharepoint 2007, windows sharepoint services, ajax control toolkit, ajax, asp.net, asp.net ajax, microsoft ajax, ajaxbasepart, web part