Although still lagging significantly behind market leaders Android and iOS, latest figures have revealed Microsoft increased its share of the UK smartphone market almost three-fold in teh past 12 months, up from 2.2 per cent to 5.9 per cent, closing on on current third place holder RIM in the process.
Note that Blackberry isn't currently supported by Waze either.
In the US, market share appears to be around 3%.
Waze simply doesn't have enough resources to devote to a platform that is less that 10% of the market.