There's a gargantuan session thinger that gets included in every page that keeps track of where you "are" in the application: each hit goes to the same URL and only the session info changes. This is great for workflow apps, but horrible for apps that benefit from an actual URL that can be bookmarked and passed around.
[link|http://www.cincomsmalltalk.com/userblogs/avi/blogView?searchCategory=continuations|HREF Considered Harmful]