It seems the latest known figure is close to 15MK...
have a look here:
http://en.wikipedia.org/wiki/Solar_core
When reading this I was a bit surprised that the power release density in the Solar core is only 11W/m3 for the core, and 0.2W/m3 for the whole Sun :-)
Very ineficient! But Sun is very big, so... we are not freezing to death :-)