The functionality I liked the best from TripCase was that you could enter the Sabre PNR and last name and it would pull the info as it existed in Sabre. So if there was a problem (airline schedule change, etc.), you were alerted to it based upon "source data." Tripit provides updates, but only from based upon the flight numbers, etc. -- it doesn't pull info from the GDS or airline records.
Anyone find any (public) replacement service to pull Sabre data by PNR?