Currently we have a cloog-ppl package in [core] as a dependency for gcc. That is based on a two year old fork of cloog to the ppl backend for licensing reasons.
Now upstream cloog  have made a new release with a new backend (isl ) that is appropriately licensed for gcc usage. This backend is preferred by cloog upstream and the gcc/graphite developers intend to fully switch to it .
To allow me to test this some more, I am bringing a package for isl and cloog into [testing]. isl can be built using piplib, but I will make a decision is that is worth doing later... These packages will sit in [testing] until gcc-4.6 is released (probably a month or two away).
I will also adjust the current cloog-ppl package to install its headers elsewhere to avoid conflicts with the new cloog package and probably do the cosmetic rebuild of gcc with the adjusted configure option to detect these headers.