The Developer Tutorials blog has an article posted today about how you can "hack" your WordPress installation if you happen to forget the password for your account:
Do you have multiple Wordpress self-hosted blogs? If so, you've likely run into a scenario where you just can't remember your password. With Wordpress 2.5 and 2.5.1 there's an annoying bug that sometimes generates passwords that don't work when you click the "Forgot Password" option. [...] Wordpress resets the password internally (in the MySQL database) but the link that it sent you to activate that password fails to connect with the database effectively locking you out of your blog. In this scenario, at least for me, all the potentially viable solutions lead to dead ends.
His six step process involves an external script (use with caution, especially before you read the source) that reaches into your WordPress install and updates your admin account and sends out an email with the resulting password.