How will this affect conversions?



you can always test user agent to see what % is this kind of traffic. If you see it rising on certain sites, and your roi dropping there, you just adjust.

Something like this might also open up $ possiblities, like itunes offers to people on iphones or xbox live offers to people on xbox360s (if such a thing exists and if 360s ever get a functional web browser).

Ideally an ad network could do this detection for you and sell inventory based on platform type.
 
if tracking and analytics can see what os's each computer is using, then it can see these OS's on these platforms. it may take a while to be able to disallow this type of traffic though