I think I dont agree much here. Its cruel to even begin to compare harmattan-meego with wp in multitasking. At kernel-level i'm sure all of them do some multitasking, true thats not the discussion.

On the app-level, even in the most basic multithreading, if you are running on a multicore processor the threads are automatically going to get divided by the processor to run on seperate cores, you dont have to do anything to tell the processor how to share the load. And you even have those apis which you can use if you want to specify which core a particular thread should execute on, but I think from a phone's perspective that will be a rarely used scenerio. As I understand (never programmed for ios), ios actually has stuff programmed in it to stop stuff from running at the same time to give a smooth user experience. They have special APIs that the programmer can use to tell the OS "hey i'm doing some special stuff in this method and please keep it running (even if at low priority) when this app goes background". Android must have such stuff in it too (not sure), specially coded to give a smooth user experience, but way better then ios i'm sure. (Although, seperate discussion, my friends were showing me their multicore android devices, was some lg phone dual core 1ghz, they had custom roms loaded, and the 3d desktop lagged a lot. Again, seperate discussion.)

Now when you talk about meego-harmattan however, as I understand (I have never used N9) there is nothing preventing one application to execute its code regardless of what any other app maybe doing. You dont have to code harmattan UI/UX to support multithreading for, say, notes/some-irc-app/gpodder/leafpad/some-console-app/multiple-web-pages/calendar/conversations-im-sending-recieving-messages etc etc to be able to work all at the same time.

For all I know, even today in 2012, harmattan-meego is the best platform to utilize multicores. Period.