USB is controlled by a SIG group. Their web site is : http://www.usb.org
Which contains more than any sane person wants to know about USB
As a development, you need a USB Vendor ID for your to identfy your product.
Other than that, I do not know if there are any addtional requirements
Lots of thanks Doc! At usb.org I learnt that I need to pay a reasonable ($2k-ish) license fee and pass some evaluation to have my (my customer's really) gizmo "USB-IF compliant and certified" and then put some stickers on the product. My customer's customers couldn't care less though. Besides compliancy and stickers; is the technology as such up for grabs, free to use commercially etc?