What this means in practice is that after 4pm BST today, some of you will see the old version, and some of you the new. You'll be able to tell the difference, because you won't be able to post to the old one. It typically takes about 24hours, maybe longer, for the process to complete. Restarting your browser/computer/modem may (or may not) help - it depends on where the old IP addresses are being cached.