This update does not affect your username and password; the change is simply that you will be directed to the new log in page which functions the same as the old one. After logging in once you will not need to re-enter your credentials when you visit another EVE Online website that also uses SSO.
We will also be doing some behind-the-scenes upgrades to the EVElopedia software and updating the Item Database to the latest version. This will require the EVElopedia to be locked for editing for a few hours while the update is in progress.
There may be a short down-time for each website while the updates are being deployed, but we do not expect it to be for very long.