Be advised that WordPress 2.9 MU is no longer a separate project from the main WordPress branch. It is continuing development as part of the main WordPress 3 branch under the name ‘multi-site’ or MS. This means that you can get all the benefits of both WordPress and WordPress MU versions by using the latest WordPress version. To help you in the process of creating a multi-user website with the latest WordPress version we have created a detailed step by step WordPress multi-site tutorial available here.
The good Search Engine Optimization process covers all of the following steps:
1. Blog Title & Taglines optimization
2. Update Services (Ping sites)
3. Modifying the Title Tags of your WordPress Theme
4. Meta Tags Optimization
5. Permalinks & Mod_rewrite settings
6. Optimization of Keywords
7. Google Sitemap creation
8. Social Bookmarking
You may review our article SEO for blogs for detailed instructions on how to optimize your WordPress website.
If you would like to start your WordPress MU Blog in a few clicks, check the WordPress MU Hosting package.