Linux Mint is experimenting with using Debian Testing as it's base. I'm downloading it now and haven't tried it yet. But this looks like a great way to give Debian Testing a spin off a live cd without having to install. Also the idea of having all the niceties of Mint on a pretty much pure Debian Testing base with the advantages of it being a rolling release sound very tempting to me.
Some of the good points...
This experimentation shows us that:
* It is possible for Linux Mint to easily switch base (if Ubuntu disappeared or went in a different way)
* A Debian Testing base would make Linux Mint faster.
* A Debian Testing base would let users transparently go from one release to another by simply applying updates in mintUpdate (release would be like simple snapshots in time)
* A Debian Testing base would be easier to maintain in the long term for the Linux Mint dev team