If you’re running WordPress, you’ve got a quick weekend project ahead.
WordPress 2.3.1 was released late Friday — a bugfix and security update. It also features support for Windows Live Writer and speed improvements in WP’s tag handling. The release notes are here.
Upgrading is straightforward: backup; overwrite; and run the installation script. Instructions are here. How to do a clean installation is here.
WordPress 2.3 was released on September 24th, featuring a built-in tagging system, update notifications, and improvements to the system’s SEO-friendliness.

2 Comments
I’m probably missing something, but I’ve yet to see a really compelling reason to upgrade from 2.1. Widgets leave me cold, and tags would only bring me more pointless search engine traffic.
To me, the big sell isn’t tags — it’s the improved URL handling and overall fit and finish. I like widgets, though not for the junky stuff many folks cram into the sidebar. It’s an easy way of managing a page, lending WP something of the power you’d expect from a traditional content management system.
Another compelling reason to upgrade is security fixes. But 2.3x may break your template, so test it first if you opt to take the plunge.
(Dave has one of my all-time favorite sites, Via Negativa.)