You almost certainly have a DS18S20P on your hands. This is a variant that only uses parasitic power, the power lead is not connected in the package. You can verify this by using another pin to trigger a scope just before you write the 0x44, you will then see the 8 bits followed by a tragically sagging voltage on the data pin.
I ran out to the FET shop and got a VN2406L (the guy said "everyone buys these", good enough for this) and wired it to another pin like the data sheet shows and everything works now.
The only sad part about this is that now you have to blindly wait 750ms for the temperature to read instead of waiting just long enough.