Pairing a good thing.
I nearly always use my iphone and my ipad together. If I'm working on something or webbrowsing, due to the lack of multi tasking, I tend to check my emails on the one, while leaving my book undisturbed on the other or what have you.
But working this way I've not needed multitasking to be honest, but I've also come to apprecate that having an extra screen avalible to show messages is a good thing. Now when out and about, if I could also use my 3G from my phone rather than requiring 2 phone connections thats a good thing.
I can also see it being great to be able to just use the screen as an extension of the smart phone. For example, keeping the music and video on just one of them. So when multitasking does finally hit the ipad, only having to keep one of the devices upto date with vast ammounts of data (over the cloud or via itunes or how ever) but being able to consume it on any device (airplay to apple TV may be) is a massive advantage.
Blackberry are doing great stuff. I hope it goes big wings and flys far.