It was so long but python 2.6 is now in Gentoo stable, here is how to upgrade.
First emerge –sync your ports tree (as of 31st July 2009).
Then update your ports _emerge -upvD world _remove -p when ready.
When emerging python-2.6.2 it will become the main python, as you can see with eselect python list.
So you only have to rebuild every ports that rely on python, simple ? Yes with python-update
Just run python-update It will run all the needed emerge for you (40 ports on my server)
_Remove the old python version(s) with emerge –prune python _(Note that removal is not mandatory, old python interpreter could coexists).
_Run revdep-rebuild _to be sure there is no remaining tools that depends on libpython2.5, then you are done, restart your apache, daemons, whatever is in Python.
PS: if you are using postgresql-8.3 as stable, you will have some problems with egenix-mx-base: a package needed by postgresql-server
dev-db/postgresql-server-8.3.7 (python? dev-python/egenix-mx-base)
There is a “with” parameter in a function, in 2.6 witch is a reserved keyword solution was to update to >=dev-python/egenix-mx-base-3.1.1.