No, it doesn't really multitask fully.
Only selected apps.
like? sms? it always brings you back to your last sms (and with 3.0 u can exit out of it or even start a new sms as it's being sent)
calender? it always brings you back to what you were last looking at
photos? same deal
camera? same
youtube would be the exception it wont start where u last left it but will show u wat you last looked at
stocks?
maps? will show you your last location u were on
calculator will show the number u last inputted
itunes and app store both pick up from where u left off
mail will open up last email u were on
safari always loads what page u were viewing when u last looked at it, and on the 3GS it doesn;t have to reload the page, even with multiple tabs open
ipod as u know will play in the background no matter what ur browsing and will even play music over most games.
so, i dont know, if you ask me if you ever exit out of any of the default apps you always get back to what you were originally doing
I'm trying to consider what modes of mutiple at the same time processing could u come up with in an iphone situation?
granted pandora running in the BG while browsing is multitasking that doesnt happen unless u jailbrake, but i cant come up with another other reason for wanting mutiple processes going on while you're on one current task