I just think we spend too much time talking about scaling and not enough time discussing virality.
If you'd like to share a story, however, on using statistical techniques to measure and act on virality, doing multi-variate testing, et al that would be very interesting.
E.g., some of Yahoo's non-search properties receive tremendous traffic but their scalability stories (while still requiring a great amount of difficult engineering work) aren't as interesting as those of Facebook or other Yahoo properties e.g., Search, Flickr.
What is your application? Are you profitable? Very profitable? (Oh god I hope you are very profitable, or some of my apps are screwed - but then again I guess it really depends on the business model and usage characteristics)