I read something about how the younger generation of kids is learning the art of multitasking. Do their homework, listen to music, IM your friends, and more. While the mix of tasks is a little different, I admit I multitask a lot. It comes with the work I do.
A typical morning for me includes attending a teleconference, reading morning email, IMing someone, and reading my RSS feeds. I can usually context switch without too much problem, though I know I occasionally miss important details when multitasking. When someone notices a context switch, you have failed to effectively multitask.
One problem with multitasking is that the more you do it, the harder it is to stop. Over the years, I find my propensity to multitask has increased. The key thing to know about multitasking is to know when not to do it. Driving is not a good time to do it. Neither is a face-to-face meeting with your boss. Neither is any time where your full attention is mandatory.