Seaside does have a gargantuan session ID in the URL, but that doesn't have to be *all* there is: the rest can be taken up with useful, bookmarkable info. I don't know exactly what your requirements are, but don't dismiss Seaside just on the bookmarking issue.
See [link|http://www.cincomsmalltalk.com/userblogs/avi/blogView?showComments=true&entry=3256899497|http://www.cincomsma...&entry=3256899497] for more.