Christo:
Quite late in this discussion, but I have found an Arduino port of V-USB here: Google Code Archive - Long-term storage for Google Code Project Hosting.
It seems as if RancidBacon has wrapped the exported functions as follows to make them compatible with Arduino's C++ environment:#ifdef __cplusplus
extern "C"{
#endif
USB_PUBLIC void usbInit(void);
USB_PUBLIC void usbPoll(void);
#ifdef __cplusplus
} // extern "C"
#endif
Thats the same thing I did 8).