Technically it is, but by the standard of multitasking we've used for 20 years now, it multitasks. Even multi-core computers multitask, since there are almost always more than even 8 processes needing to run at any given time.

Multitasking is what we expect high speed CPUs to do. (switch back and forth very rapidly between running processes)

Multiprocessing is what you get when you have multiple cores.

Even the iPhone multitasks, although that capability isn't exposed to the user outside of a few apps that keep at least part of themselves alive (exchange, the phone, the music player) even when they are in the background.