WordPress MU

I read somewhere a while back someone changed some code and all the sub blogs of WordPress MU acted as seperate installs of WordPress MU.

So it was setup like:
main blog MU > sub main blog MU > Regular blog

I've tried searching for the post I saw in the past but cannot find it.

Does anyone recall this or know how I can accomplish this?

Thanks in advance.

search multi site manager and domain mapping, etc

I'm not looking to map domains to the install.
Basically, each person who signs up under the main blog gets there own WordPress MU install.

Multi site manager does it. that's how to get the sub-blog to be its own MU "site".

http://wpmu.org/wpmu-enterprise/