No it is not. Where did you get that idea?
Damn... I must have missed that removal. :( I know for a fact it used to be.Archive should be brought back. It still exists in the form of still exisitng at
ftp://ftp.debian.org/debian-archive/ but the most recent version is slink.Even if archive.debian.org is down, potato could still have been put in that folder.
Woody must remain in the main archive as old-stable for at least a few weeks because some people will need need it for dowloading utilities for some last second upgrade prepearations. For example somebody may wish to download a utillity to create a compressed backup of the current state before trying to upgrade. While dd|bzip2, may do the job it is not ideal. I'm sure there are other reasons too.