You can see how many kills have been registered on each platform at the Coral Sea challenge part of the Battlefield 1943 website, here: http://www.battlefield1943.com/
Currently the 360 leads with over 39 million kills versus ~20.7 million on PS3. Once each platform gets to 43 million kills they get a new map.
The ratio last I checked was around 1.9-1 in favor of 360, and has even been growing slightly in 360's favor (it was around 1.8-1 a couple days ago).
Obviously this is extremely unproffesional, but still a interesting pseudo-data point I feel.
If this was a USA data, it would be inline with the install base, however being worldwide data, where the 360 has a lesser install base lead (perhaps 3:2) I feel it's quite impressive for 360. Although one could also surmise military shooter fans are biased to 360.
