Apple's .Mac service will be updated today.
.Mac subscribers have been informed of this within the support area of the site, which explains the downtime to be for "scheduled maintenance".
Maintenance is scheduled to begin at 10am (PST) today, around the same tome as Apple CEO Steve Jobs climbs the stage at the Moscone Centre to deliver what may emerge as one of the most important Worldwide Developers Conferences yet.
In related news, thirteen new .Mac HomePage templates have been added to Apple's subscription-only service.
.Mac subscribers now have 80 such pages available for their use. These include larger iMovie templates, six new movie templates and four new photo album templates.
"The latest designs expand your options for showcasing photos and movies, including new widescreen templates for high-definition iMovies. You can now take advantage of the new template "suites" Graphite and Archival to create a whole site - albums, writing, site menus, and more - unified by one design theme", Apple states.