Symbian has pthreads support, but it sucks, yesterday i discovered it has a maximum number of threads you can create, that is
void *dumb_thread(void *)
int error = pthread_create(&t, NULL, dumb_thread, NULL);
will end up returning error 35 (EAGAIN) in pthread_create after some calls, depending on the phone it can be 20000 or 60000, and yes, that's a lot of threads, but if you are using threads for fire and forget jobs it's relatively easy to hit that number, so i've been forced to implement a thread pool just to workaround yetAnotherSymbianBug.
And yes, this has nothing to do with KDE, except that the more i code in Symbian the more i appreciate the rock solid API provided by KDE and Qt