Unfortunately, many agile, fast-moving companies have aggressively resisted or rejected the principles of "big-A" architecture, which is most notably characterized by EA frameworks, formal architectural documentation, centralized technical oversight, and top-down (or inside-out) standards setting and enforcement.
An "architectural" mindset will ensure that successful agile companies are able to scale to enjoy the benefits of their market positions and transition from startup to sustainable company. Unfortunately, therein lies the problem: how do you know when to invest in architecture? Except at enormous cost, you can't code in quality (maintainability, scalability, reliability) at a later time, but investing too much in these quality properties at the wrong time in a given lifecycle almost guarantees failure.
This presentation was given at SATURN 2011 in Burlingame, CA.