Soapblox does.  They install the basic software on their server and give you access.  It's up to you to "skin" it and make it look the way you want.  I suspect that if you want help with that, that can be arranged as well.  Of course, it's based on Scoop.

I've set up and configured blogs on drupal, Movable Type 3.x and 4.0, and Wordpress.  I think that Drupal is powerful but not necessarily user-friendly.  The documentation support for it is (or was as of 6-9 months ago) less than wonderful.  It may be overkill for what you want to do.  

There is an ASP that does drupal hosting that may be of interest:  bryght.com.   One of their founding guys wrote a goodly portion of the drupal core.  Their website is well-designed.  Their documentation is good. They offer varying levels of service based on how much or how little you want to do on the technical side.

Movable Type 4.0 has a new community configuration that allows you to have multiple blogs/diaries associated with the main blog but I have yet to install that.  

There are MT hosting sites out there as well but I haven't investigated them since I installed it on my own or client's server accounts.

I think that MT, Drupal and Scoop each have their strong points depending on what you want to do.  And part of that calculation should also be based on the amount of traffic you anticipate receiving.

I don't know, I just know that DKos uses Scoop, which seems to do practically all you want.