packages

I hope this question is not too general.

I remember reading on one of the postgresql lists a while back (either
-general or -hackers) the mention of "packages". As I understood at the time,
a package enables the installation of third party extensions in a packaged
way (not unlike a software package) so that you could easily add, for
instance, a set of xml functions (just an example).

It was also my understanding that packages would work closely with schemas,
which also makes sense.

Does this mean, perhaps, that package support is planned for the 7.3 release
(which includes schemas), or is it too involved to add at this stage? Is my
understanding correct? Do the developers even agree that packages should
exist?

regards,
jeff