In one of my previous blogs, I mentioned the final build number for Visual Studio 2005 was 8.0.50727.42.
The way it worked in the past was our build numbers were 8.0.YMMDD.00. When we came close to shipping, we froze the first three digits and then only incremented the last number (the dot number). This allowed greater compatibility with previous builds and minimized the churn in our build and code.
What this means is on July 27th, 2005, we started the final push to the final build. From there, we built 42 times which is how we came up with 8.0.50727.42.
One interesting tid bit. The original code name for the .NET Framework was "Project 42". Coincidence that we ended up with .42? :)