bigal83:
I've also read that the J3 jumper is obsolete for the newer updates like 2011-05-28, but you mean that it is first in the later updates it is used?
In the official USBasp releases, the jumper always overrides the ISP clock rate.
If the newer code is used you can set the rate through the commands over the USB
interface. But even if you do set it with a command, the jumper still overrides that setting.
So while you don't necessarily have to use the jumper to get a slower clock, it still
works with the newer firmware.
--- bill