Are there X10 receptacles that are capable of dimming?
No, however, you can use the plug-in lamp modules to have that capability or wire the receptacle to an X10 dimmer switch, (or use an inline X10 fixture module, LV6376/XPXPDF). Note: Ensure that only incandescent lamp loads are plugged in to the receptacle when wired directly to an X10 dimmer switch or dimming fixture module.