WordPress MU

Is it possible to have something like this:
subdomain1.subdomain.domainname.com
subdomain2.subdomain.domainname.com
subdomain2.subdomain.domainname.com
Basically, what I want to know is the possibility of Admins of subdomain.domainname.com being able to add further subsites to their own site.
I know I am trying to really stretch the functionality of MU, but if its possible to do, why not try...It would be useful for my Users.

Try registering for new blog at: subdomain.domainname.com/wp-signup.php
It created subdomain of subdomain for me.

Thanks qza,
Yes, it does :)))
Wicked.
Don't know the implications though. Going to check out if everything works normally on the subdomain's subdomain.

I just tried with with 2.6 version, but it never works. User activation link doesn't work. I guess I should go with subdirectory option for now...

Basically, what I want to know is the possibility of Admins of subdomain.domainname.com being able to add further subsites to their own site.

Don't think this part is possbile on a single WPMU installation, but subdomains of subdomains certainly is.
E.G. WPMU installation at blog.mysite.com
Users blog is at fredspalce.blog.mysite.com

Yes, you are right. They have one at http://blogs.law.harvard.edu/
The blogs appear in sub directories, for example:
http://blogs.law.harvard.edu/pannone/