BillO:
Since the DS1825 will only sink about 4 or so ma, I'm not sure the resistor voltage divider will work.
Yeah. I was doodling maybe just using a diode on my output pin. The 4K7 1-wire bus pull-up gives me a 3.3V high signal, and when I want to assert a low I can do so through a small signal diode. When it's time for the DS1825 to talk, I put the output pin in hi-Z and listen on the other pin. I think as long as the DS1825 is powered through its power pin, the source current I assert on the bus does not matter and the 4K7 bus pull up should be fine.
I really like the mosfet idea, but the only ones I have on-hand are large power mosfets.