WordPress is coming up to a huge milestone in its history. For a long time, WordPress and WordPress Multi-User (WPMU) were serpate entities, sharing the same code base, but largely different functions. WPMU’s core function was to house multiple blogs, such as a network like WordPress.com. WordPress’ main function was to house a single blog.
WP and WPMU are merging.
This announcement took place in May 2009 at WordCamp SF. It was and still is, a huge announcement (and process).
Yesterday while watching #wordpress-dev (where all/most of the core developers meet to talk about WordPress), there was a lot of chatter about WordPress 3.0, which is when WP and WPMU will be merged.
Today, we can see tickets being closed where there is the introduction of WPMU’s slight code changes into the normal WP.
Something to note, it’s not WPMU being merged into WP, but the other way around. WP is being merged into WPMU. The key to the success of this merge is to keep WP as efficient as possible so that it doesn’t get too bloated.
Here is an example of something we’ll see along the way of how WordPress is changing.
[sourcecode lang="php"]if( !is_site_admin() )
unset( $submenu['plugins.php'][10] ); // always remove the plugin installer for regular users
unset( $submenu['plugins.php'][15] ); // always remove the plugin editor
unset( $submenu['themes.php'][10] ); // always remove the themes editor[/sourcecode]
The new updated and merged code base is going to have to take into account there will be an overall admin along side of normal blog administrators. Changes along these lines are what we will be seeing throughout the next year for what WordPress is becoming.
I’m really excited to see where WordPress is going. It’s been a wild ride for the past 6 years and I’m ready for another 50 years on WordPress 
Update: The WPMU options, such as multiple blogs within a single installation, will be opt-in only. You will have to enable them in the wp-config.php file before they are available. This is good for the average user so there’s no confusion as to how the blog should be administered.
Do you think we are going to see older plug-in’s “break” with this new version? My understanding is that many of the older plug-in’s that still work with WordPress, don’t work with WordPress MU.
Jamie Dolan
Pre 2.6 plugins, the really old ones, tend not to work on MU, but I’ve not had any problem with ‘modern’ ones.
I’m looking forward to this, personally. I really hope we can ‘opt in’ after upgrading our WP single sites
Merge two blogs into one MultiSite run setup. How nice!
That’s a good point. Some plugins do break with WordPress MU, but work fine for normal WP. So this will definitely be a good move as it will encourage plugin developers to update their older plugins so it works on the new platform, which is WP and WPMU merged together.
I’m really excited about the merge, a lot of good things happening right now.