Going beyond the general coolness factor of showing the end to end process that t-shirts go through at Spreadshirt and that in itself being a good advertisement, I think it did an amazing job of humanizing the company. This is critically important because both CafePress and Spreadshirt through making it so easy to create a custom t-shirt, did a great job of commoditizing their own businesses at the same time. Essentially they both looked like black boxes where you uploaded images and t-shirts came out the other end, so in the end it came down to price, and no one wants to be in a business where price is the only deciding factor. One company that managed to differentiate themselves in this regard was Goodstorm, by focusing on non-profits, and smaller more socially conscious companies Goodstorm already built a connection with customers that went beyond costs, and connected on the importance of their work together.
In the end there is no doubt that the concept of print on demand for t-shirts and the like is a really amazing thing, helping people get their ideas out there, my only hope is they continue working on the quality.