In previous versions of DNN the tabid was used in the URL to find the page requested.  The rerewriter in a fresh ce 05.04.01 install does not use the tabid anymore. I find this breaks my links in search engines and other links if I change pages name(or a parent and then edit the child page). Is it possible to have the rewriter leave the tabid in the links so they dont break when you change the page title?  Is it safe to assume that  the URL http:ex.com/tabid/99/thischanbeanything/this-could-be-anything.aspx will always resolve to tabid99?

Chris' advice is correct, you can remove the humanfriendly attribute in the web.config file to revert to the old style tabid included Url.

You are correct in that any Url with the tabid in the path will resolve correctly to the tabid.

Chris is correct in that it is bad for SEO in that the Url is less precise and you will end up with duplicate content problems if you use different Urls with the same tabid (which results in two Urls pointing at the same page)

If you want to migrate to human friendly urls, you'll need to redirect the tabid urls to the new human friendly Urls.