A general question to the of SharePoint Designer 2007 user community: Can SD 2007 be used to create websites with rich user experiences like that shown on the updated Southwest Airlines site (http://www.southwest.com/) Look at either the Book A Flight or View or Change Your Flight widgets along the right-hand side. Is this beyond the scope of SD 2007's design capabilities
I'm a business user, not a developer but is it possible given some custom Ajax development
Although there is no out of the box support for Ajax (more specifically the ASP.NET Ajax extensions) at this time, adding Ajax is possible in Sharepoint. ASP.NET Ajax will apparently be supported in the Sharepoint Service pack 1 but I do not know when this will come out.
On the Southwest site you mention, I suppose you refer to the hide/show of the content beneath each of the links in the right of the page. This is currently arlready available as a control in the ASP.NET Ajax Toolkit so I suppose integrating this even today should not be that hard.
Without going too much into the developer details, there is already something available called the Sharepoint Ajax Toolkit which helps with the implementation of Ajax in Sharepoint.
Hope this helps
Posted: SharePoint - Design and Customization, SD 2007 and Ajax-Style Interactivity