That's the same with the iPhone, always has been. Apple just didn't let third-party apps freely multitask like Android does (there is controlled multitasking now). WP7 is starting in Apple's initial position, no third-party multitasking. A good example of useful multitasking would be playing music and running your GPS navigation at the same time, and then being able to check your Facebook/WWW/etc without stopping the others.
I'm not sure about a GPS navigation application but I believe that Zune, IE, imbedded radio have the music and any Facebook/WWW multitasking issues covered - because they are all 'native' applications. In fact, I've read you can even see some FB status updates on the main screen tiles if you want.
Not sure how it works with one 3rd party app running while other native apps are running in the background.
Wait, just a few posts earlier you stated WP7 doesn’t multitask, now you admit it multitasks like the iPhone. Which is it? Does it multitask or not?