This plugin may already be obsolete by the time you read this, but I found a couple of functions that weren’t provided by the default WordPress-MU API that you may find useful in your own WordPress-MU development.
New Plugin: MU-Helpers
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Tag Archives: wordpress mu
Rough Guide to upgrading WordPress MU 2.9.x to WordPress 3.0 Multi-Site
** Update** Skip to the comments. One Assumption on my part led to a lot more work than is needed. This guide does work, but as Ron (@wpmuguru) pointed out, I went around the block to just go next door. Even smart people are dumb sometimes 
The WordPress 3.0 betas are kicking around and for projects still in development, upgrading now will save you the trouble later after the site is in production. Upgrading Single Site WordPress installs to 3.0.x is as easy as ever, but now that WordPress ยต has been rolled into the main WordPress code base it takes a bit more work to “cross-grade” to the new WordPress 3.0 Multi-Site features.
This is a rough guide to upgrading WordPress MU 2.9.x to WordPress 3.0 Multi-Site. That means that I’m largely pulling this from recent memory and may skip a step or state something inaccurately. Feel free to heckle correct me in the comments.
Nginx Virtual Host Recipe for WordPress MU / BuddyPress
More than one person has asked me for my Nginx Virtual Host recipe for WordPress Multi-User and BuddyPress, so I’m posting it here. The attached virtual host definition is feature complete and works for me on a number of production sites.
Be sure to change domain.tld to your actual domain name. The wildcard record will allow your site to respond to ANY sudomain request, which may not be something you want.
You’ll also need to change the path to your log files, as well as the path to your public webroot folder. Finally, up the client_max_body_size to match your upload_max_filesize and post_max_size settings in php.ini.
Finally, this assumes you are running your PHP fast cgi process on port 9000.
This is the recipe for WordPress MU / BuddyPress. I’ve also posted one for WordPress (single site) and Drupal.
Download Nginx vhost Recipe for WordPress Mu and BuddyPress
Please post ways to improve this in the comments. I use this on a number of production sites, but there is always more one can do. Thanks to all of the blogs and articles that I ripped off helped me understand Nginx and got me started.