Well, Leica marketing department is not doing it, so I will promote this special offer for them:
Free Leica D-Lux 4 battery (North America only)
Read the small print for more details - my local dealer told me that I can still use this promotion with the ongoing Leica mail-in rebate.
Leica's website provides more info on all Leica Demo Days. Check with your local dealer - this is a good deal and another way to support your local Leica shop.
The value of the D-Lux 4 battery is US $68.21.