Epson's SureColor F2000 can print a t-shirt in just a few seconds. At Comic-Con in New York, they had one on display: I emailed a picture, rested my iPhone on its transparent lid, and recorded this real-time video of it running one off in less than a minute. Like a goddamn office memo! It does full color tees, too. Specs:
• 5-color Direct-to-Garment Printer
• All new Ultrachrome® DG inks
• Revolutionary EPSON PrecisionCore® TFP® Print Head for extreme print quality and production speeds
• Maximum resolution of 1440 x 1440 dpi for white ink and 1440 x 720 for color inks
• Large garment imaging area up to 16" x 20"
• Designed for simple maintenance and high reliability
• Garment Creator imaging software included
It was on special at the show, but you'll have to pay the full $20,000 price now, suckers. Another caveat: you have to prep the tees chemically, and with a heat press, before using it. Here's some more video from a different show: