>I'm in a stage 3 chroot, following manual... Have all the appropriate mounted(proc), profile sourced, env-updated, date is >accurate, timezone set... 
>
>>>> Updating Portage cache:
>Traceback (most recent call last):
>  File "/usr/bin/emerge", line 3004, in ?
>    conf = portage.config(config_profile_path=portage.settings.profile_path[:], \
>TypeError: unsubscriptable object
>
>Nothing is emerge-ing either

Are  you sure you have got enough memory? I forgot to swapon my swap partition and that did the trick for me