Many applications in e.g. Powertools (vic, rat, ...) use tcl/tk 8.0. It isn't always trivial to change them so that they'd work in 8.3. Currently they have their own tcl/tk packaged within the SRPM. Perhaps a compat version of tcl/tk 8.0 should be packaged and included in either main packages or on powertools CD?
SInce this a .0 release for the Red Hat distro, no compatibility libraries for tcl are planned, rather providing an upgrade path for all known tcl utilities.