[VincentVinturi]

You can use subdomains if you want make three distinct 'portals' for your site.

E.g.

- http://group1.yoursite.com
- http://group2.yoursite.com
- http://group3.yoursite.com

But these would effectively be 3 separate WordPress installs, unified by your "parent" domain.

Otherwise you can just use 3 categories and split your posts among those categories.

Then each segment's blog would just be a link to that category page.

You can use a WordPress plugin that removes the /category/ slug to simplify the permalinks.