The current stable version of WordPress is 2.8
Do you have a weblog that you don’t want to break, but don’t mind if it did? Maybe you like to check out the latest experimental version 2.9, that is being programmed during daytime and which can be downloaded at night. The updates go by the romantic name of “Nightly Builds”, which is exactly what they are… Be careful not to set fire to your blog! We’re talking pre-alpha code here! 🙂