I have a MacBook Pro and an iPhone, so I definitely don't need one. It is certainly a supplemental device mainly for consuming information and media. But saying that, a guy in my office has one and I certainly want one - especially after seeing it in action.
I think it's an amazing step forward in technology and the way we interface/interact with said technology. Just a large iPhone without the 'phone' part? Yes! But that is no small thing. We can only imagine how useful this will be 2, 3, or 4 iterations down the line. Add a front facing camera and you've got yourself a portable video conferencing device. Apple's new 'retina display' tech will be amazing when it reaches this device. What they do in their labs keeps on producing some truly useful and innovative technology and I see the iPhone and the iPad as embodiments of this innovation. For this alone I think the iPad can't be ignored.
From a business perspective- we all need iPads to ensure that our work is relevant to the format, and to ensure that we're constantly evolving our output to suit it, along with pcs, macs, iPhones, Blackberries etc.
From my perspective (i.e.business development) it marks a dramatic shift from schlepping around my laptop and portfolio to every client meeting. Soon, I'll be able to present my pitch, email over a pdf portfolio and showcase our multi-format capabilities all in one go. Genius.
The only irritating this is waiting for the second or third generation machine to ensure all the niggles are ironed out.