Captain Kirk, USS Enterprise, gets a "Godspeed" wish! Lucky chap ! you might say...but for us mortal souls "Good Speed" is what we simply crave for....but then what exactly is a Good Speed (velocity) for your agile mission ? do you know ?
Following the typical sequence for agile projects, we all estimate the story points and get the total size estimate for the project. The team velocity (or the speed) as measured historically allows us to get the number of iterations required and this turns into the project calendar release plans (voila...GM milestone here I come) ..sounds familiar.
But what about the historical velocity ? is my historical velocity good/bad ?
Scott Ambler suggests that measuring the historical velocity itself is not the end. Do Not measure velocity.
Measure the velocity trend line (== acceleration ) !
What is happening in your project ? Does the velocity trend line go up or down for your project?
If your project velocity trend line goes UP then you are in good shape (and have a "Good Speed") but if the velocity trend line goes down then you need to understand the reasons and retrospect (deeply as Esther Derby remarks).
I think that this observation is important otherwise people can start measuring the velocity ONLY for various teams across the organization at any point and it may not be all fun.
Scott Ambler also suggests that the velocity is "unlikely to be gamed". But I disagree with Scott on this since the focus on measuring up trending velocity may have it's pitfalls.
Some of these in my view could lead to the team breaking stories prematurely...adding more in the same iteration and/or shifting the additional story points to a bigger number over subsequent iterations. Beware these shifts !!
Understanding this comparison across multiple projects, both with upward velocity trend lines would need another discussion and I have to get back to Captain Kirk...(oh) Captain Kirk, no offense but I am wishing Chandrayaan Godspeed this time.