can the usb interface act like a jatag in circuit

can the usb interface act like a jatag in circuit emulator.

Being able to step through code and use GCC is the main reason I didn't buy avr duno yet.

If the io of the usb adapter could make it a incircuit emulator it would be awsome.

I know their proably is hardware and software changes nessisary to do that.

If timming is a problem could a real time OS feature be added to DSL linux to get that problem fixed?