I have just upgraded to the latest version of WordPress. This one is 2.5. I followed the instructions and everything seemed to work fine.
These are the short instructions, if you want more check out the extended upgrade instructions. If you experience problems with the Three Step Upgrade, you may want to review the more detailed upgrade instructions.
You may notice a few refinements but overall it will do nothing to enhance the fine writing style and witty insights that this site depends on to survive!