Dave:
High-profile, complex web sites and applications require an exponentially larger testing effort than your average blog or "brochure site". I'll share some principles and techniques that are universal to any software development effort - not just Drupal.
Irakli:
Drupal Multisite is a powerful and mature tool for creating platform deployments of Drupal-based web-systems. However creating a release structure that allows atomic deployments of individual sites within a multisite is a somewhat less explored problem. Presented blog post describes one such approach that uses Subversion version control and a set of bash scripts for Linux to automate the process.
