For completeness and future reference, I should include this link to the Battery Charging v1.2 Spec and Adopters Agreement, USB Implementers Forum

From the USB 2.0 Wikipedia entry for USB 3.0;

The 1-amp rated Samsung AC charger supplied with my Galaxy Nexus has pins D- and D+ shorted.

The cheap china car charger I got from DX has proper resistor networks to signal 500mA max per port (2 USB ports). I just now hacked it, adding 200ohms across D- D+, to trick my phone into charging at (up to) 1amp from it, instead of trickle charging as it normally would.

A friend of mine makes a cable that can switch in and out the short between the data lines. This is nice so I don't have to modify any chargers. Dealextreme makes cheap versions of his cable, but he says those are junk.

I took a USB extension cable and modified it, then just swapped that in and out as needed. Same idea.