Not surprisingly, the various teams that contribute to the Windows product have been hard at work planning what goes into potential future versions of Windows.
As a part of that planning process, we've been collecting all sorts of data, and sifting through it to try to figure out what are the most compelling scenarios for the myriad of customers of Windows.
I was looking at the feature planning timeline and it had something like:
|x/y||Scenario Description Complete|
|x/y||Preliminary Feature Description|
|x/y||Full Feature Description Complete|
When I saw "T-Shirt Sizing", I got really excited. There's an old adage that says something like "A new product isn't done until the T-Shirts have been ordered", so I thought it was cool that the planning process had integrated ordering the group/feature T-Shirts right into the process.
Unfortunately that wasn't the case :(. Instead, what the people who designed the planning process meant by "T-Shirt Sizing" was categorizing the effort to implement the feature into "S, M, L, XL, XXL, etc". The basic idea was to get a rough feel for the amount of effort associated with each feature.
T-Shirt Sizing is an "interesting" metaphor for development effort. Normally metaphors speak to fundamental truths - "All the world's a stage, And all the men and women merely players, They have their exits and their entrances" is a metaphor that maps life to the actors in a play. But I'm really not that sure what T-Shirt Sizing has to do with the amount of effort involved in a software project. You might as well use "Ice Cream Scoops" for your metaphor - single scoop is a small amount of work, double scoop is more, triple scoop is still more, banana split is really big.
Personally if I were doing the planning, I'd not bother with the cute name and simply describe it for what it really is "Feature Size Guestimate". But that's just me, and I don't get to decide these things.
Obviously this is my opinion, the opinions of others may vary.