running beta 4.0, downloaded pandora and started playing music, and as soon as i went to switch to another app, the music stops and switches to the app, and doesnt start again until i launch pandora again.

so im guessing pandora hasnt been updated to support the audio multitasking like it was shown during the 4.0 preview.

or am i crazy and im not doing it right?

Of course the current version does not support multitasking (the app needs to be compiled with the new SDK for that). It'll be out with the official iPhone OS 4 launch...