Clearcase VC for NT Emacs - Extension to the Emacs lisp version control package, not just for NT. - http://www.fukt.hk-r.se/~flognat/vc/
Emacs ClearCase integration - This is a ClearCase integration package for GNU Emacs (implemented as a vc.el backend) that works with recent versions of it (including CVS version). - http://vc-clearcase.sourceforge.net/
ClearCase VC (CC-VC) - An extension of the GNU Emacs VC package which understands the ClearCase configuration management system. This package is not officially supported, but the author is willing to fix bugs in it as time permits. - ftp://rtfm.mit.edu/pub/cc-vc/