You guys have been busy while I've been asleep (in Australia).
I understand duplicated content is bad for SEO, is this still the case if it's on a subdomain of the main domain? I believe so..
As for why i need it, I'll provide my situation, see if that helps, I'm not sure WordPress MU Sitewide Tags will work for me.
I have a main site, a sports news site, the top of the WPMU tree is where all my content is submitted, the main blog/news site, I have about 40 categories all nested nicely, and I display what I want from the top of the (category) tree and down at specific sections, the news can be about a sport or within that tree about a specific league and within that tree about a specific team, there are links to various parts of this category tree displaying the content all over the main blog, depends what is popular in the sport world right now, some linked from the homepage etc
The Subdomains in my WPMU site are all sports leagues or teams,if people wish to go direct to a subdomain and only focus on one team they can, instead of duplicating my content from the main blog, I would like to also have the category of that team or league, pull the contents into the sunbdomain (not just one category either, on the sub-site for a team I pull the team category into a page, and each of the leagues they are involved in into there own pages linked locally from the sub-site)
One option is to just link them back to the main blog, would be easier, but then they get pulled away from that sub-site and loose focus.
Hope that explains things and someone has a solution?