We finally fixed a nagging power consumption issue related to the TWI (nee I2C) on early rev Si of the nRF51822. You can see the PAN for all of the gory details. Suffice it to say, the TWI wasn't shutting down correctly, leaving us with an unexpected +1mA current draw. We poured over some code that Nordic uses in the nRF Smart Remote 2, and adapted it for our needs. Problem solved. 
 
We'll post some "TWI to XXX sensor" examples shortly (IR Temp, Barometric pressure, Humidity, Ambient Temp, etc).