I just updated the TLC's copy of Drupal, used to host 10 Drupal-powered websites, to the latest Drupal 4.7 RC3 build. Upgrading the code took under 2 minutes (SSH into the server, curl the updated code down onto the server, then tar -xzf and move the appropriate files into place). Add another 5 minutes to run the update.php script on each site, and you've got 10 Drupal sites updated in 7 minutes flat.
The 4.7 release is really a smoking upgrade from 4.6 - it hardly feels like the same software. Modules install and update their own database tables now, piggybacking on the core update.php upgrade script, making it soooo easy to update the code and dozen-or-so added modules.
The multi-site hosting feature is one of the biggest things I love about Drupal. Initially, I was maintaining separate copies of Drupal, with modules etc. painstakingly added to each one and kept in sync. I was essentially managing my own distro of Drupal, which wasn't the most productive thing to be doing. After some prodding from Patrick, I read up on the sites feature, and now every single one of our Drupal-powered websites runs from a single copy of the code. All modules and themes are automatically available to each site, making maintaining each one pretty much trivial.
I just realized - it's taken me longer to write the blog post describing how easy updating Drupal is, than it took me to run the update itself...