Personally I maintain a rsync copy of the current tree - this has advantages as the tree is in a constant state of flux and it's easy to update when needed.
There are iso "snapshots" available
here if you just want a quick way to get started although the one they are hosting as of now is dated 11/4/08 and so is not totally up to date. There were a lot of changes made 7/11/08 which won't be included.
The current tree is a moving target and is meant to be for testing the latest changes made to the next release version. This is not something to be installed and then left as fixes and updates are constantly applied. Obviously any feedback from bugs on an out of date install will be of no value.
It is by definition not meant to be installed on production equipment as no stability can be expected. In saying this the tree is remarkably stable but you should check out the
CURRENT.WARNING given here and also the
Changelog.
As T3slider said - you may mirror current using Alien Bob's scripts which have the facility to create an ISO from the mirrored tree or serve them up via the nfs/ftp/http facilities of setup. This is the approach I would recommend. Then you can rsync update the tree regularly and apply the changes to the live system when they are rolled out.