Superseded by the GSPCA driver in the mainline kernel. Development now at http://linuxtv.org/ [Formerly: Linux device driver for SPCA50X based USB cameras (Intel PC Camera Pro)]
Java access to USB, currently using kernel 2.4 Linux-USB support. There is a "core" API for accessing USB devices, and simple tools including a USB viewer in Swing. Applications are being developed separately, including digital camera support.