I think it means that your web app can survive being slashdotted. So, a lightweight C10K-capable frontend, all static content on a CDN, everything heavily cached, database queries optimized to the hilt, etc... etc... Some people think that just using a NoSQL database is sufficient, but there's much more to it. Interesting talk on this stuff (was posted on HN earlier): http://ontwik.com/python/django-deployment-workshop-by-jacob...
