Take A Look At What OffsiteStatus Can Do For You
OffsiteStatus allows you to schedule mainenance windows in order to let your customers know of upcoming downtime. These will be visible on your status blog via a widget to the right of the page:
Customers that have subscribed to your status updates via email notifications or RSS will be notified as soon as you post the status update, not when the maintenance window begins.
When the scheduled maintenance window begins your OffsiteStatus blog will automatically be updated to show that the site is currently in a scheduled maintance status. When the maintenance window is over the site will automatically put your status back to what it was before the maintenance window began. If your maintenance finishes early you can easily update the status yourself you reflect this.