The Mono team pulled a 21-day 12-16 hour-per-day hackathon to implement Silverlight for Linux that they have dubbed Moonlight. 21 days with a group of good hackers doing double shifts and working on the weekends. Just counting hours, each contributor will have put in about as much work as a regular 9-5 employee does in two months. We're assuming the entire team is composed of clever people - only clever hackers care to work so much. And lets assume there's a handful of people working on it (seems reasonable from the task list). So about a years worth of quality development delivered in 3 weeks by a small committed team with no external constraints and full concentration.
Sounds about right to me. Miguel de Icazas war story blog post is a great read.
Posted by Claus at June 21, 2007 3:51 PM