packaging a GCC binary distribution so it can be installed at arbitrary locations?

[Gary Funck]

> 
> Yes, with recent versions of gcc you can move the entire tree around
> and the gcc driver will still be able to find the various internal
> executables and header files. [...]

Ian, thanks.

Which versions qualify as "recent" above?  GCC 3.4, or 4.0, or both?
Is there any documentation on how the new packaging mechanism works?
If this was discussed on this list, would you happen to know approximately,
when (so I can do a search of the archives)?