Hey Attis,

From what I have seen with my own blogs is this:

When I have set-up a series of sub-domain blogs using WPMU it has increased my Google Page Rank and helped with Alexa ranking also.

From what I have been told is that the SE view these sub-domains as really being an extension of the main domain and thus the content counts towards the main domain.

One thing I did learn is that over-used cut & paste content can hurt your rankings.
(I use Blogs Organizer to propagate my sites with my Sponsor's RSS feeds)

That being said...I found a plugin called "Uniquefier" at: http://goscript.net/featured-article...er-plugin.html that changes the words to a numerical code within the backend.

It works really cool.

Hope that helps - Jay